I was reinstalling everything on a laptop this morning when I noticed that the Office 2010 Professional Plus public beta is now available in both 32-bit and 64-bit versions; I believe this was just 32-bit earlier. The Office 2010 Professional public beta, however, is still only 32-bit.
To be clear, when you visit the Office web site and click on the Office 2010 Beta | Download the beta link, you're brought to the Office 2010 Beta page, from which you can click a "Get It Now" button (in the upper right) to download the beta. If you hover over this button, you'll see two options pop-up:
For home, small business, and school - This will trigger a download of Office 2010 Professional (which includes Word, Excel, PowerPoint, Outlook, OneNote, Publisher, and Access) in Click-To-Run format, a virtualized environment that sandboxes Office from the rest of your PC but looks and works normally otherwise. This option is still 32-bit only.
For enterprise and mid-sized business - This will trigger a download of Office 2010 Professional Plus (everything above plus InfoPath, SharePoint Workspace, and Communicator) in a "normal" full download that's about 650 MB in size. You can choose between 32-bit and 64-bit versions. (64-bit only works on 64-bit versions of Windows Vista or 7.)
Anyway, I've gotten a lot of email from people who have been looking for a 64-bit version of the Office 2010 public beta, so here you go. I suppose it's possible this 64-bit link has been there for a while, but I'm not positive, and I don't recall that being the case when the beta was first announced.