BioWare's apparently maxed out the storage capacity of DVD's with Mass Effect 2. The game will be spread over two discs for the Xbox 360 and PC versions.

BioWare's Chris Priestley explained on the game's forum that the PC version will be a standard install and require no disc swapping. The Xbox 360 version will not have an install but will require a swap. Yes, only one swap.

"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," said Priestley.

If you complain about changing discs once over the course of a 40+ hour game, you're lucky you didn't play RPG's back in the nineties. BioWare's first RPG, Baldur's Gate, was spread over seven CD's (eight if you bought the expansion) and you had to swap back and forth when you traveled to different regions.