It looks like the long forgotten era of disc swapping has once again returned, there's confirmation the on Mass Effect forums that Mas Effect 2 will ship on 2 DVD's, with a third included in the special edition, though that's just video and not part of the game.

Ok some details for you.

1 - Yes, there are 2 game discs for both the PC and Xbox 360 versions, both the Collector's and standard editions.

2 - There is a 3rd disc with the Collector's Edition. This is a movie DvD containing making of and other bonus information.

3 - The PC version is a standard install. You install the information from both discs and then play with 1 disc in the drive. No swapping.

4 - The Xbox 360 does not have an install and does require disc swapping during play.

5 - 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. You do not swap back and forth. 1 swap and then done.

6 - Why 2 discs? Answer: Because you cannot fit this much awesome on one disc.

Thanks Kotaku