The following is not even a rumour, just something I came up while walking to work this morning.
Everyone's asking for it, and BioWare is refusing to talk about it - the possible PC version of Mass Effect. Now, if this would ever be made at all, what I would do if I was working for Microsoft or BioWare, would be this: I would wait until the second part of the trilogy is out on Xbox360. Then, after a couple of months when it's sold enough, I would announce the PC version. The Xbox crowd would obviously buy the third part for the console as well, so I would have secured that part of the market. The next thing would be the second part for PC, with the last part of the trilogy following at the same time for both systems. Makes sense, doesn't it?