The framework and tools team has been hauling A over the last few months to get this to you and they are justly proud of themselves.  A key factor in the beta is that you can't deploy to your Xbox in this version - this is mostly to try out things while developing on your PC.

Get setup here if you are new to it all:

http://creators.xna.com/en-us/3.0beta_mainpage

If you have the previous CTP or run into problems, our amazing setup pm Aaron Stebner's blog is particularly helpful:

http://blogs.msdn.com/astebner/archive/2008/09/16/8954720.aspx

Get help from folks in the forums here:

http://forums.xna.com/forums/

In a move that entirely trumps When Cods Collide in 2.0, we have Goat Attack by John Kennedy on the new 3.0 stuff:

http://blogs.msdn.com/johnkenn/archive/2008/09/17/goat-attack.aspx

Live it vivid!