A good few months ago I wrote about SP1 for PerformancePoint and getting this working on SQL Server 2008. There were a number of attempts, and with a great deal of hacking, I got an untested environment set up, however this was not very stable and never fully tested. SP2 is due for release in December, and there are mentions of a Beta available on the web, although unavailable through MSDN, or Connect. It seems that the two promises of SP2 are Hyper-V compatibility and SQL Server 2008 integration.
A few good resources for this are as follows:
http://hmorgenstern.spaces.live.com/Blog/cns!28A6BE83102A0EB3!419.entry and http://performancepointing.blogspot.com/2008/11/performance-point-server-sp2-pre.html