Is mindfulness the path or the goal?

Mindfulness is very important, but it is part of the path, not the goal. It is the seventh of the eight factors of the Noble Eightfold Path, and the path can be grouped into three trainings. The wisdom training, the morality training, and the concentration training. Mindfulness falls under the training of concentration.

In MN 29, the longer heartwood simile discourse, the Buddha talks about the different reasons for practicing and compares them with different parts of a tree, and he warns against thinking that the parts of the path (including morality, meditation, and wisdom) as being the goal. It says:

"Just as if a man in need of heartwood, seeking heartwood, wandering in search of heartwood — passing over the heartwood of a great standing tree possessed of heartwood — cutting away the sapwood, were to go off carrying it, thinking, 'heartwood.' A man with good eyesight, seeing him, would say, 'Ah, how this good man didn't know heartwood, didn't know sapwood, didn't know inner bark, didn't know outer bark, didn't know twigs & leaves! That's why he, in need of heartwood, seeking heartwood, wandering in search of heartwood — passing over the heartwood of a great standing tree possessed of heartwood — cutting away the sapwood, went off carrying it, thinking, "heartwood." Whatever heartwood-business he had with heartwood, his purpose won't be served.'

"In the same way, monks, there is the case where a certain son of good family, out of conviction, goes forth from the home life into homelessness, [thinking,] '...Perhaps the end of this entire mass of stress might be discerned!' Having thus gone forth, he encounters gain, offerings, & fame. He is not gratified with that gain, offerings, & fame, his resolve not fulfilled. He is not intoxicated with that gain, offerings, & fame, not heedless about it, and does not fall into heedlessness. Being heedful, he achieves consummation in virtue. He is gratified with that consummation in virtue, but his resolve is not fulfilled. Because of that consummation in virtue he does not exalt himself or disparage others. He is not intoxicated with that consummation in virtue, not heedless about it, and does not fall into heedlessness. Being heedful, he achieves consummation in concentration. He is gratified with that consummation in concentration, but his resolve is not fulfilled. He is not intoxicated with that consummation in concentration, not heedless about it, and does not fall into heedlessness. Being heedful, he achieves knowledge & vision. He is gratified with that knowledge & vision, his resolve fulfilled. Because of that knowledge & vision he exalts himself and disparages others: 'I dwell knowing & seeing, but these other monks dwell not knowing & not seeing.' He is intoxicated with that knowledge & vision, heedless about it, and falls into heedlessness. Being heedless, he dwells in suffering & stress. This, monks, is called a monk who grasps the sapwood of the holy life, and with that he falls short.

"Furthermore, there is the case where a certain son of good family, out of conviction, goes forth from the home life into homelessness, [thinking,] 'I am beset by birth, by aging-&-death, by sorrows, lamentations, pains, distresses, & despairs, beset by stress, overcome with stress. Perhaps the end of this entire mass of stress might be discerned!' Having thus gone forth, he encounters gain, offerings, & fame. He is not gratified with that gain, offerings, & fame, his resolve not fulfilled. He is not intoxicated with that gain, offerings, & fame, not heedless about it, and does not fall into heedlessness. Being heedful, he achieves consummation in virtue. He is gratified with that consummation in virtue, but his resolve is not fulfilled. Because of that consummation in virtue he does not exalt himself or disparage others. He is not intoxicated with that consummation in virtue, not heedless about it, and does not fall into heedlessness. Being heedful, he achieves consummation in concentration. He is gratified with that consummation in concentration, but his resolve is not fulfilled. He is not intoxicated with that consummation in concentration, not heedless about it, and does not fall into heedlessness. Being heedful, he achieves knowledge & vision. He is gratified with that knowledge & vision, but his resolve is not fulfilled. Because of that knowledge & vision he does not exalt himself or disparage others. He is not intoxicated with that knowledge & vision, not heedless about it, and does not fall into heedlessness. Being heedful, he achieves a non-occasional liberation. And it is impossible, monks, there is no opportunity, for that monk to fall from that non-occasional release. [1]

"Just as if a man in need of heartwood, seeking heartwood, wandering in search of heartwood, cutting away just the heartwood of a great standing tree possessed of heartwood, were to go off carrying it, knowing, 'heartwood.' A man with good eyesight, seeing him, would say, 'Ah, how this good man did know heartwood, did know sapwood, did know inner bark, did know outer bark, did know twigs & leaves! That's why he, in need of heartwood, seeking heartwood, wandering in search of heartwood, cutting away just the heartwood of a great standing tree possessed of heartwood, were to go off carrying it, knowing, "heartwood." Whatever heartwood-business he had with heartwood, his purpose will be served.' http://www.accesstoinsight.org/tipitaka/mn/mn.029.than.html

This Sutta makes it clear that it is incorrect to identify a part of the path such as mindfulness as somehow being identical with the goal. Mindfulness is a tool, not the result.