When the March Madness edition of NCAA Basketball 09 was announced many people wondered why it was exclusive to the Xbox 360. EA Sports didn't make any comments as to the reasoning behind that. News that came out today though may provide the basis for why that decision was made.
MTV has an article about how publishers have become frustrated with the charging of bandwidth fees for both paid and free content on Sony's Playstation Network. It appears that this is another (unrealized) benefit to the paid XBL subscriptions that now publishers are hesitant to provide content for PSN because they have to foot the bill for it.