if you go to www.office.com, select the the Get Office2010 Beta link from homepage, you're brought to the beta site. From there, click Get it Now. In the choices, you have to pick "For home, small business and school". Click-to-Run delivery is available for Office Home and Student and Home and Business. Other products (like Office Professional) are not enabled with Click-to-Run at this time.
Hope this helps.