I’ve been receiving this question frequently this week so I’m sure others are asking as well:
Can I upgrade prerelease versions of Microsoft SharePoint Server or Microsoft SharePoint Foundation 2010 to the release version when it becomes available?
No, the prerelease (beta) versions of Microsoft SharePoint Server and Microsoft SharePoint Foundation 2010 are for evaluation purposes only and upgrade to the release version of these products when they become available is not supported. This includes both the binaries and databases.
Bill Baer, Technical Product Manager, US-SharePoint
Thanks for calling out. I assume TAP customer are in the same boat as well.
TAP/RDP customers should confirm with their account representatives supportability for upgrade from prerelease to RTM.