To clarify further, for those confused, the PS3 version of UT3 will feature keyboard and mouse but PC to PS3 cross play has not been decided on yet. Rein listed some hurdles that need to be jumped before the feature could be implemented during his interview with Joystiq. One of those hurdles? Control differences. So with that fixed, it's a possibility. They just haven't decided yet. Yes, we're really driving that point home.
Keep those rumours coming and we'll keep debunking them. Probably.