Brian, I was able to install on a Windows 8 machine from the SAAS 6.3 Preview server. After a reboot, I tried to uninstall, but it failed with this error in the procedure log:
FAILED in processing THEN step 3, Execute File, with error Spawn Failed, "C:\Program Files (x86)\AVG\AVG2012\avgmfapx.exe" /AppMode=SETUP /Uninstall /DontRestart /UILevel=silent /LicenseKey=8KASEYA-NL7DD-LS0LK-YW8EA-6CGF7-*****-E70N
I opened ticket CS147064 to address. I will post any updates I get.