Microsoft has offered up the first Internet Explorer 9 patch via Windows Update. KB2448827
is all about improving reliability and stability, and you should be able to find it on your Update screen by clicking through to view optional updates (or by navigating to Control Panel\System and Security\Windows Update\Select updates to install
in Explorer). It's a little odd to see Microsoft do this -- they're typically not big on delivering patches to beta apps the way competitors like Google and Mozilla do. Perhaps there's a paradigm shift underway in Redmond.
If you're looking for some real
IE9-related excitement, the recently-leaked Internet Explorer 9 beta 2
(which may, in fact, be an RC build) might be more up your alley. It's floating around the usual places you find 'community releases' of Microsoft apps.