It would appear that unless a title either ships first on the Xbox Live Arcade or simultaneously with PSN Microsoft may refuse to publish it.
Microsoft also demands that the game contains no extra content in the PSN version of the title or again it may refuse to publish.
European Xbox Boss Chris Lewis told Eurogamer;
“We’re a little biased, so obviously we’re going to look to protect our own space as best we can and get exclusivity,”
“Whilst I can’t be specific about the terms and conditions, you can be very confident we seek to maximise our own advantage to ensure the playing field is even, and certainly plays to our advantage wherever possible.”
“As you can also imagine, our partners have to be mindful of the relationship they have with all platform holders, and they need to be equitable. But there are contractual situations where we get agreement with different people to do different things, and through what we have available on Xbox Live, we are able to offer things other people can’t offer, that allows that exclusivity and unique elements to it that might not otherwise be available elsewhere.”
“Titles for Xbox 360 must ship at least simultaneously with other video game platform, and must have at least feature and content parity on-disc with the other video game platform versions in all regions where the title is available,”
So if you have been waiting for one of those PSN exclusive titles to finally make the jump across to Xbox 360, you’re going to be waiting a very long time.