I was really disppointed that the oblivion Plug-ins were only on Xbox and PC, when, so many people I met wanted them on PS3. Wouldn't it be better to have them on all platforms?
The official DLCs should be released on all platforms, although there might be some time exclusive stuff like the Dead Money DLC for Fallout: New Vegas.
But fan-made plug-ins will obviously only be for the PC.
I'm not a big fan of the "exclusive to one system" dlc. I don't really care if one system gets a dlc before another.. Just as long as they all eventually have a chance for it. I mean I understand that the game makers can get some quick easy money for allowing a system to have a first crack at extra content and that funding is a necessary evil.