Microsoft have now released the final major pre-release of Windows Vista to people in the Customer Preview Program. It will be available to non CPP (those who didn't get Beta 2) in the coming weeks, those that used Beta 2 can use their existing key on RC1. Or it can be installed for 14 days with no key, after which you'll be prompted to enter the key and activate.
My few words of advice from using it for the last week:
nVidia's drivers are still terrible; on mobile platforms they're extremely bad and I've had better luck using with Windows XP drivers. On my M200 using the XP drivers fixed poor performance, screen corruption and sleep issues.
ATI have released a set of RC1 drivers on their website, however most people have been having better performance with the in-box drivers. If you can live without the control panel I recommend sticking with the in-box drivers. ATI's drivers do not currently support OpenGL.
Creative's drivers are still poor, on x64 they're still not signed and so you will need to disable driver checking on start up. But multichannel sound is no longer limited to stereo.
The in-box VIA RAID drivers for the VT8237 appear to have issues when using SATA drives, better performance was achieved using the Windows XP drivers.
Windows Mobile Device Center has yet to be released, but I am told it will be available soon.
Other than that if your last build was Beta 2 5384 you'll be blown away by the quality improvement. More details can be found here and the download can be found here.