Okay. Let's keep this just the facts, as everyone knows what they mean. The tech specs for Bioshock 2 are out. They're reasonable enough. There's also some fun DRM. Online verification via SecuRom, with an install limit (15 machines, admittedly). To save the game or play online, you need to be logged into Games for Window Live. This still applies on Steam - so SecuRom and Games For Windows Live are needed in addition to the Steam client. Hmm.
UPDATE: 2K Community Manager Elizabeth elaborates over at the forums. In short, it will be doing the standard Games for Windows Live activation - as in, you can play and save games offline without achievements. SecuROM is only a disc-check method for the retail copy. While final details of Steam are forthcoming, that may imply it won't be there. Hmm.
Comments thread... go. Let me and Edwin Starr provide the soundtrack.