Yes, the official Star Trek/Doctor Who crossover has been announced unofficially. Notice, this is not fan fiction, like a hundred other Who Trek crossovers, but the official. I should also note another reason I’m filled with gamma rays of excitement (off-topic reference alert) about this: It’s not just Star Trek meets Doctor Who, it’s Star Trek: The Next Generation meets Doctor Who.
As far as we know at the time of this writing, the characters featured will be the current cast of Doctor Who, The Doctor, Rory, and Amy, as well as the entire main cast of Star Trek: The Next Generation. Here I lay in hope that it will feature Q as well, but that has not been announced. Come on! The Doctor VS Q? I’d pay handsomely for that, and don’t tell me you wouldn’t!
The official announcement is most likely going to be made in one week’s time at the Gallifrey One convention.