Confirmation has come down from Chris Priestly of BioWare on how many discs
Mass Effect 2 will be. First off, the game will come on 2 DVDs for both the PC and 360 version. The PC version is the standard install both and play with one DVD in the drive. The 360 has a disc swap that occurs at a carefully planned part of the game. If you think you could install both discs and just use one, well you can't. You're going to have to swap discs on the 360.
Seeing as there's an option to install on the 360, I wonder why BioWare didn't make ths as an option. Disc swapping is a minor annoyance in my view but it's not like the 360 doesn't have a way to let you bypass this should you have enough hard drive space. So, if you were wondering now you have the answers.
Oh, why does the game need 2 discs? As Chris says, "Because you cannot fit this much awesome on one disc." I salute you Mr. Priestly.
Thanks
Kotaku.