I have some information about release dates on WMP 11 for XP that no one else has. This info was obtained from a Microsoft employee who I can't name but was able to give me this info. If you know other MS employees, they may be able to confirm this info by digging a little bit through Microsoft's internal knowledge base (employees only):

Microsoft is planning a Public Preview Beta of Windows Media Player 11 for XP on Wednesday, May 17th.

The Hotfix