Username or EmailPassword
as they would also have to backport shell enhancements, FS enhancements, etc...
What shell enhancements? What FS enhancements? There will be none when Vista first arrives. Those are slated to come later. That said, I haven't heard anywhere that Aero will be backported. The poster meant Avalon and that is going to be backported.
Shell enhancements: Explorer is getting changed quite a bit, and that is part of the shell.
FS enhancements: Metadata, search. Not WinFS stuff, but still enhancements.
How about the ability to handle meta data, and to be able to edit it from the shell.
Or, how about things like the "word wheel". New search functionality, this all comes with Vista.