Can people in Heaven communicate with each other?

In Revelation, there are several instances of people communicating to one another in heaven. John was brought into heaven in a vision and records what he saw there.

Revelation 4:10-11

The four and twenty elders fall down before him that sat on the throne, and worship him that liveth for ever and ever, and cast their crowns before the throne, saying, Thou art worthy, O Lord, to receive glory and honour and power: for thou hast created all things, and for thy pleasure they are and were created.

There, the 24 elders communicate to God in song.

Revelation 5:5

And one of the elders saith unto me, Weep not: behold, the Lion of the tribe of Juda, the Root of David, hath prevailed to open the book, and to loose the seven seals thereof.

There, one of the 24 elders speaks directly to John. Read another extended conversation in Rev. 7:13-17.

Revelation 6:1

And I saw when the Lamb opened one of the seals, and I heard, as it were the noise of thunder, one of the four beasts saying, Come and see.

There, John hears one of the cherubim speaking to him, giving him an order.

Revelation 22:6

And he said unto me, These sayings are faithful and true: and the Lord God of the holy prophets sent his angel to shew unto his servants the things which must shortly be done.

There, Jesus speaks to John in heaven.

Revelation 22:8-9

And I John saw these things, and heard them. And when I had heard and seen, I fell down to worship before the feet of the angel which shewed me these things. Then saith he unto me, See thou do it not: for I am thy fellowservant, and of thy brethren the prophets, and of them which keep the sayings of this book: worship God.

Finally, this is an example of an angel speaking to John in heaven.

Mawia and Alypius gave a good answer here for a mainstream follower. That would be that mainstream teaches the immortality of the soul. They would say that the person must go somewhere after death. The other side, which is sizable and includes 7th Day Adventists, teaches that the soul is not immortal and the dead are dead; it is like sleeping or being unconscious.

The bible has several passages that are very interesting concerning this topic. The most notable is probable the one Mawia quoted.

After six days Jesus took with him Peter, James and John the brother of James, and led them up a high mountain by themselves. There he was transfigured before them. His face shone like the sun, and his clothes became as white as the light. Just then there appeared before them Moses and Elijah, talking with Jesus. Matt 17

Most Christians would agree that Elijah did not die (2 kings 2) so his presence is therefore not revealing for this topic. For the mainstream belief in the immortal soul it is obvious that Moses' soul was just as lucid and able as his body. For the lesser taken view of the mortal soul, there is an argument (although weak, in my opinion), that Moses was resurrected. This is one of the 7th Day Adventists sites. They are one of the larger groups that believe the soul is mortal and the video in the link covers their logic on Moses' resurrection very well.

The next most notable passage is of Saul and the medium of Endor. Saul was a good king who had turned wicked, and in desperation turned to a medium to consult his dead counselor Samuel. Something does actually appear and what it is I will not try to say but, again, both sides have a ready answer. See this post on the topic.

Now the next one is probably more commonly quoted than the story of Saul and the medium and it is also the one Alypius chose to use on this post. It is actually a parable of Jesus where two men die and see each other and father Abraham in the after life.

“The time came when the beggar died and the angels carried him to Abraham’s side. The rich man also died and was buried. 23 In Hades, where he was in torment, he looked up and saw Abraham far away, with Lazarus by his side. 24 So he called to him, ‘Father Abraham, have pity on me and send Lazarus to dip the tip of his finger in water and cool my tongue, because I am in agony in this fire.’
“But Abraham replied, ‘Son, remember that in your lifetime you received your good things, while Lazarus received bad things, but now he is comforted here and you are in agony. And besides all this, between us and you a great chasm has been set in place, so that those who want to go from here to you cannot, nor can anyone cross over from there to us.’
“He answered, ‘Then I beg you, father, send Lazarus to my family, 28 for I have five brothers. Let him warn them, so that they will not also come to this place of torment.’
“Abraham replied, ‘They have Moses and the Prophets; let them listen to them.’
“‘No, father Abraham,’ he said, ‘but if someone from the dead goes to them, they will repent.’
“He said to him, ‘If they do not listen to Moses and the Prophets, they will not be convinced even if someone rises from the dead.’” Luke 16:19

Mainstream, immortal soul theology would say there really is no argument here. They are in an afterlife conversing and these are the very words of Jesus. The less taken, mortal soul theology would argue that this was a parable and it is not even about death and the after life. It is meant to show that the Prophets and the Law (the books of the Old Testament) should be enough for anyone to believe. If they do not believe those then even someone coming back from the dead would not convince them to believe. See this post and this post for further study on this particular passage.

Both sides have good and bad points, but that is your decision. I have provided the groundwork for you to learn about both and make an informed decision.

As for describing heaven as 'like Nirvana' I cannot find nor have I heard of any such passages.

Sure they can.

Matthew 17 (NIV) ¹ After six days Jesus took with him Peter, James and John the brother of James, and led them up a high mountain by themselves. ² There he was transfigured before them. His face shone like the sun, and his clothes became as white as the light. ³ Just then there appeared before them Moses and Elijah, talking with Jesus.

In this story, the spirit of Moses was talking with Jesus who was in the flesh. Elijah was also in flesh because he was taken to heaven alive. Although the place was on Earth, if they can communicate on earth, I don't see any reason why they would not do the same in Heaven.

In Revelation 21, the future new heavens and new earth, I would conclude there will be communication based on this description.

22 I did not see a temple in the city, because the Lord God Almighty and the Lamb are its temple. 23 The city does not need the sun or the moon to shine on it, for the glory of God gives it light, and the Lamb is its lamp. 24 The nations will walk by its light, and the kings of the earth will bring their splendor into it. 25 On no day will its gates ever be shut, for there will be no night there. 26 The glory and honor of the nations will be brought into it. 27 Nothing impure will ever enter it, nor will anyone who does what is shameful or deceitful, but only those whose names are written in the Lamb’s book of life.

As the commenters have already pointed out in response to other answers, the various points in the Bible which might be seen as answering this question are ambiguous. The only passage that I've seen that claims to answer it definitively comes from outside of mainstream Christianity. In the book of Doctrine and Covenants--a collection of revelations and teachings accepted as canonical by the Latter-Day saints, and held to be authoritative along with the Bible and the Book of Mormon--we read:

And that same sociality which exists among us here will exist among us there, only it will be coupled with eternal glory, which glory we do not now enjoy.
-- Doctrine and Covenants 130: 2

While these revelations are not accepted in mainstream Christianity, to the Latter-Day Saints this passage provides comfort and reassurance that those we count as friends and family and loved ones in this life will be able to maintain such interpersonal relationships with us throughout eternity.