As you may have noticed in our updates since, the listings have been removed from the website.
In a gist: both games are now 360-PC exclusive again... for the foreseeable future anyways.
While a L4D2 appearence on the PS3 was always going to be very unlikely, BioWare's refused to rule out Mass Effect appearing on the console someday. But for now, that "someday" is a pipedream.
Catch more through the first link.
L4D2 is out on November 17, while Mass Effect 2 is out in Q1 2010.