Check it out:
http://technet.microsoft.com/en-us/library/bb124558.aspx is now updated with documentation for Exchange 2007 SP1.
I've been living and breathing in the SP1 world for the past couple of months, between some cool projects I've been working on here plus doing the DPM book. It's neat to see it getting closer and closer to release; they've got some really nice work in there.