Guys,
When I was buying my tickets at my local Cineplex (Coliseum Mississauga, for those of you in the GTA), the manager who works there, who happens to be a buddy of mine, confirmed that the 2 hour and 45 minute running time is official. It came straight from WB in the information they sent out for event planning purposes prior to distribution.
Additionally, a quick search online shows that every major theater chain is now reporting 165 minutes. BFI, AMC, Cineplex, Allocine... It doesn't get any more official...
...Unless, of course, you go straight to the official TDKR Imax website:
http://www.imax.com/movies/m/the-dark-knight-rises-the-imax-experience/