I felt lucky and applied the 6.5 beta as an upgrade over the custom 6.01 RC2 to see what happens. Machine was configured to server-only mode, only one user existent.
1. It does not seem to upgrade anything, the older packages are still in use (like samba 2.2.8 or e-smith-base 6.0.4), nothing new, rien. I expected it to upgrade the rpm's at last.
2. It actually does something: no remote access over ssh or https possible, you can use the local server-manager. Most services start as normal, dns seems to be broken ("unable to bind udp socket")
This was just a spare time test and should not be taken serious - although i wonder about the complete failure of the 6.5 "upgrade" function.