These links aren't live *yet* but will be soon...
Install Internet Explorer 8
Internet Explorer 8 can be installed on Microsoft Windows Vista® Service Pack 1 (SP1), Windows Vista, Windows XP® Service Pack 2 (SP2), Windows Server® 2008 and Windows Server2003 Service Pack 2 (SP2). Downloads are available from the following locations:
Internet Explorer 8 Beta 1 for Windows Vista and Windows Server 2008
UPDATE: The downloads just went live Enjoy!