The latest IE7 beta 2 Preview is available here at Microsoft.com.

You must uninstall any previous IE7 installs before installing.

The

bug has been fixed in this version, but sites such as rails.techno-weenie.net still don’t display properly.

UPDATE: They may have fixed this bug, but they really fubarred the back and forward buttons.. what a mess. This isnt a beta, it’s more like an alpha.