@Robert Hallock
XP SP2 was effectively a rewrite of the OS though, to harden it since SP1/gold was woefully inadequate. They postponed development of Vista for that.
That doesn't rule out the possibility that Win7 SP1 will not contain feature updates like the ones shown in the winmain_sp builds. Reason being, is that if these features WERE initially planned, but were scrapped/postponed due to time constraints, threes no reason to believe that the major groundwork for it was already laid down. Microsoft may simply have been forced to have these features unimplemented by the RC cutoff date - That's when the code was effectively frozen, with only bug fixes left. I'm still 85% certain this SP will contain feature updates. You don't need to get the link, I know of that particular comment, but I still believe due to these reasons that 7-SP1 will be an interesting update to the OS.