This is already out on the 360 and looks stunning. The PS3 version was delayed because they were having a hard time getting it up and running well. Word is, the PS3 version of Rainbow Six: Vegas is being downgraded graphically compared to the 360 version because they can't get the same performance out of the PS3 that they are able to get out of 360.
I can't wait to see how this game looks on PS3 when it finally comes out. I am afraid Sony fans will be crying.
This isn't the only game on PS3 that multiplatform developers are having performance issues with. List of games already out on 360 that have been delayed on PS3 due to development issues:
F.E.A.R.
Oblivion
Rainbow Six: Vegas
Brothers in Arms
GRAW 2