No, it's not official. Just wishfull thinking on the part of the writer of the next Star Trek movie, tentatively titled (get this) Star Trek.

(From scifi.com.)

Personally I think they should cast unknown actors for the parts, but I do understand why they should get a 'big name' actor. They bring the people in. (Other than the Trekkers.)

I'm not sure who would fit the 'bill' (pun intended) for Captain Kirk. Matt Dillon, perhaps? No one really seems to fit.