score:9
Physicality is not specified at all. Although you could make a case that online, we are in some manner physically present to each other. :)
However, if you are together, praying, but gathered over great distances, I don't think there's any technicality in play, here. God doesn't work in technicalities, but in what's in our heart. So, I figure that yes, virtual gatherings also do count.
There are plenty of examples of people throughout the world using telecommunications to pray together. And I have never seen anyone question the idea that Jesus wasn't actually present. To the contrary, it always is understood that He is. So I would treat this as a common understanding.
Upvote:2
The primary context (Matt 18:15-20) of this passage is about correcting other believers. It's about when another believer sins against you and how you should attempt to bring them to repentance, to repair your relationship with them and to repair their standing in the church. It is not, primarily, about any generic gathering of believers.
I believe that what Jesus is saying in this and the previous verses is that when his followers work together, if they can come to a consensus then it will be the will of God. It's not directly explained here, but I would understand this to be through the work and influence of the Spirit. So when there are two or three Christians together, united in a desire to serve God faithfully, Jesus will be there to enable them to do just that.
So I don't think anything has really changed through technology. The unity we have as believers is because of the Spirit, and technology doesn't change that of course! Jesus is always with Christians, because his Spirit lives within them. The idea that anything we can do will change whether Jesus is with us or not is ignoring the Holy Spirit!
And in the context of church discipline, it too can work through technology. Getting the advice of other believers is always valuable, even if you can't see them in person. But I think it will always be better to meet in person if you can, especially when you are discussing the alleged sins of other believers.
Upvote:5
A small number of people may gather in a fancy building, on a street corner, in a coffee house or library, or on the telephone (or yes, on the internet) for worship, praise, and service. Of course, that's the promise of this verse.
It's important to take this verse from Mt 18 in context, though. It comes right after the verses on church discipline, where Jesus urges people to use appropriate means to cope with disputes, avoiding making a big public deal about things that can be handled faithfully by a small number of people.
As is often the case with things Jesus says, there's a streak of radicalism here. Jewish tradition and practice calls for a minyan -- a gathering of ten -- for prayers. Here is Jesus, in the Gospel written for the Jewish community, saying two or three is plenty.
Finally, @Mason Wheeler made a good point. Please don't mistake Christianity.SE for a congregation. If you don't have an in-the-flesh congregation, please consider finding one. Christianity is most definitely an in-the-flesh religion and spiritual path.