Test Drive Office System 2007
http://www.microsoft.com/office/preview/beta/testdrive.mspx
Looks like using a Citrix client through a broswer window Microsoft has given you a chance to play with the 2007 Microsoft Office System. I would tell you how great it runs and looks but my computer has chosen not to connect to it today. :) Maybe tomorrow.
Thanks to Jan Tielens for this information.
Shane - SharePoint Help