I'd like to figure this out as well. I have this tutorial I haven't been able to try yet.
"I got this to work, but it's no where near as elegant as with XP and Vista via the User Profile "copy to" method above:
Customize a user profile as needed
Go to Control Panel and create a new dummy admininstrator
Reboot, log in as the dummy admin
Browse to C: and go into the Folder settings and Show all hidden/system files
Browse to C:\Users and CTRL-drag the Default folder to make a second (backup) copy of it
Browse to C:\Users and CTRL-drag the customized user profile to make a second copy of it
SHIFT-DEL the original Default folder
Rename the customized folder copy to Default
Create a new dummy admin and reboot/log in to test it
I've not tested this extensively yet but this seemed to work with the exception that the desktop background pic was gone leaving a black background. I fixed this easily by re-selecting the correct background pic.
I really hope that MS restores the previous method as this seems very sketchy to me and I'd hate to have to use this in a production environment"
Windows 7 RC1 Default User Profile