A little bird (Ned Pyle) at AskDS told me that ADMT 3.2 is released!
The software can be downloaded here: http://www.microsoft.com/downloads/details.aspx?displaylang=en&FamilyID=20c0db45-db16-4d10-99f2-539b7277ccdb
One of the limitations of ADMT 3.1 was that it couldn’t be installed on Windows 2008 R2, ADMT 3.2 now can. Another limitation was that you had to install it on a domain controller to be able to migrate sidHistory using the command line. I hope they solved this issue. This and other issues are described more in detail at KB976659: Known issues that may occur when you use ADMT 3.1 to migrate to a domain that contains Windows Server 2008 R2 domain controllers