GM actually has the update info
online and publicly available (thanks codeman). All you need is your VIN # and you can see it (should be the same). I assume your dealer can use these to get the full details.
Part Number CVN Description
20861681 0000A80A New software for improved operation including proper handling of WMA DRM music, addition of the play/pause button and RSA support, and improved Zune/PFD connection robustness.
20840959 0000A24C New software to address: USB sorting/indexing issues; Bluetooth interface/implementation improvement; Apple iTouch implementation/interface issues
20824078 0000EB10 Operating system
From the looks of it, there's 3 versions. Some interesting changes in there.