BioWare’s confirmed that Mass Effect 2 will arrive on two discs, with the 360 version featuring a disc swap during play.
“Even though there is a disc swap, it occurs at a carefully planned place in the game (that does not interfere with gameplay) and is done once,” Chris Priestly, community coordinator of BioWare, said on the game’s forum.
“You do not swap back and forth. One swap and then done.”
The PC version’s a two-disc install.