Sign up for Windows Home Server Beta 2
Via the Windows Home Server blog:
"While previous releases have been tested by 1000+ Microsoft employees and some of our hardware and software partners, we are now starting to invite a broader group of external testers to participate in Beta 2."
You can sign up here (no places guaranteed) and peruse the Windows Home Server Forum.
In case you've not heard about Windows Home Server but want to learn more, check out stopdigitalamnesia.com and this post describing a short history of the product's development.