If you want the upcoming expansion to Bethesda's hit RPG Oblivion, Shivering Isles, don't bother heading to ebgames for a preorder: it's going to be download only. Bethesda's Vice President of PR Pete Hines explains why in this Gamasutra interview:

"To be honest, we didn't have any other options with how to distribute Shivering Isles, at least not at present," commented Hines. "The 360 does not allow stand-alone expansions to work with another existing product, making the only option to be to download."

He then added: "We wanted to do a version for the retail market, but the fact of the matter is that the console simply can't do that yet. If that becomes an option in the future, we will certainly explore it, but as of right now we've been told that it would take a lot of extra work by the folks at Microsoft to get that option available."

I'm not sure which part of moving information off of a disc instead of moving it off of a network is too hard for Microsoft, but let's give them the benefit of the doubt. Maybe they fired the only guy who remembers how the DVD drive works. Honestly, I'd rather just download the thing anyway: who needs more game cases sitting around the house collecting dust? I will miss getting a new paper manual, though.