Gabe Newell shared Sony's stage at the PlayStation press conference yesterday that Portal 2 will be Valve's first in-house PlayStation 3 project and that it'll have the "best version of Portal 2 for console," basically already ruling the Xbox 360 version as sub-par.
The reason for this is that the openness of the PlayStation 3 has allowed Valve to integrate Portal 2 for PS3 with Steamworks, which means "auto updates, community features, downloadable content, and more."
Regardless of which platform you'll be playing it on, Portal 2 should be great. Check the new trailer and gameplay demo (from IGN) below.