I've not yet even installed it, though, waiting for Windows7 RTM first, getting the necessary beta-cleanup done by the Win7 installation. But downloaded the files already, there's a load of them again. Links to everything needed are on the Silverlight site http://silverlight.net/GetStarted/ along with installation instructions and a lot of useful information.
Go get it! At least from my experiences with the beta, it's great!
To be continued... (as soon as I get my hand on this one too - got a lot of new stuff going on now)