As Next Best Geek reported earlier, it looks like the Silverlight 3 Beta SDK and Tools for VS 2008 have been made available for download.
There was also a link to a new Blend Preview, but the link appears to be broken. Maybe this is being saved for after certain annoucnements at Mix09.
Anyway, get youself over to these links and check out the new goodies;
Runtime:
http://go.microsoft.com/fwlink/?linkid=143433
Silverlight 3 Tools for Visual Studio 2008 SP1:
http://www.microsoft.com/downloads/details.aspx?displaylang=en&FamilyID=11dc7151-dbd6-4e39-878f-5081863cbb5d
Documentation:
http://msdn.microsoft.com/en-us/library/cc838158(vs.96).aspx.