Root access is gone on Lion Server 10.7.1 after update from 10.7 Under 10.7.0 Server I was able to activate the root user and I was able to login to my Mac Mini Server i7 as root.
Now after I did the update to 10.7.1 Server, this capability has disappeared . I'm able to du a "su root" with the coresponding password, but I'm nomore able to login through the login window.

Just as an additional information.
If I try to change the root password with the Directory Utility I get an error message in the system logfile, but not in the Directory Utility.
The error is like the following line:
changing root password failed: Error Domain=com.apple.OpenDirectory Code=5100 "This authentication method is not supported" --> This is a translation from the german output!!!

What's going wrong?
You shouldn't have to re-enable root after an upgrade, but perhaps there is a bug.

Have you tried performing the "little dance" Apple asks us to do for enabling root now that the update is over?

http://support.apple.com/kb/ht1528