Get it while it’s hot, folks (this was just released today!):
http://www.microsoft.com/windows/products/winfamily/ie/ie8/readiness/Install.htm
The beta comes in the following flavors:
Internet Explorer 8 Beta 1 for Windows Vista and Windows Server 2008
Internet Explorer 8 Beta 1 for Windows Vista x64 Edition and Windows Server 2008 x64 Edition
Internet Explorer 8 Beta 1 for Window XP SP2
Internet Explorer 8 Beta 1 for Windows Server 2003 SP2
Internet Explorer 8 Beta 1 for Windows Server 2003 SP2 x64 Edition and Windows XP SP2 Pro x64 Edition
Links are all currently active, so go have fun! For those wanting some info, here is a link to all the new goodies you get:
Internet Explorer 8 – New Features
EDIT – Installed (Windows XP SP3):
Updates soon!