As Matt noted on the migration blog a working copy of the toolkit specification has been released.  You can download it and leave feedback from this link:

http://msdn2.microsoft.com/en-us/vstudio/aa948851.aspx

 If you have feedback on migration scenarios for version control, work item tracking or other products (test, office, web, file systems, etc) please check it out and let us know.  We are still actively developing the toolkit and your feedback is very important to us!