It seems Mass Effect 2 is not only coming to the PS3, but the PSN as well. On its release date, Mass Effect 2 will be available for download form the PlayStation store. It will be the exact same version that comes on the disc. It comes will at the DLC included in the package, Overlord, Lair of the Shadow Broker and Kasumi. It also includes the interactive comic of Mass Effect one so you can import all the decisions from the first game into your Mass Effect 2 game.
To my eyes it would be better to get the game on disc not only because of hard drive space, but also the time it would take to download the whole game. Still it is nice to have the option.
Mass Effect 2 comes to the PlayStation 3 and the PSN January 18th.