With the FO3 DLC it was announced a considerable time before release that they would be released for XBox/GFWL as an exclusive. Everyone was aware of that (well those who bothered to read the information), and yes, there was a lot of unhappiness about it.
There has been no such announcement this time so we can only assume that if there are any DLCs they will be released for all platforms around the same time period.
So... technically that should clear up the whole assumption that the developers had difficulty programming for the PS3? I never read anything about an actual exclusivity deal, and whenever asked, Bethesda was hush hush on the whole thing and would never comment. A reference would be nice.
I agree that any planned DLC this time around will be released on all platforms the same time. However, as a precaution, I'm going with 360 and PC this time.