Long rumored… now it is confirmed.

From Gizmodo.

R2-D2 in Star Trek. Via Gizmodo
R2-D2 in Star Trek. Via Gizmodo

There is a high-res image available at Gizmodo, or just go watch the movie. This is apparently in the scene where the Enterprise comes into Vulcan space and runs into all the space debris.

From the article:

Can you see him floating there, on the left, right below the huge arrow that I also missed when I saw the movie? That’s obviously him, a fact that has been confirmed to me by one of the movie’s sequence supervisors at Industrial Light & Magic

… Yeah. Another reason this movie rocked.