The version falsely leaked as Office 2010 Beta1 has a problem with the uninstaller. If you get the message “This product installation has been corrupted” then I found a good way for you (Thanks to Vikas Narula) to uninstall it manually.
Vikas:
“The Problem is a missing file in the installation folder of office 2010. Office 2010 has an Setup Controller directory and uses the directory to check the installed components. please check the directory "C:\Program Files\Common Files\Microsoft Shared\OFFICE14\Office Setup Controller\Groove.en-us\". if you have no "Setup.xml" file there please copy the file from the "Groove.en-us" directory of the source files to this directory and test the uninstallation again.”