Well here my Problems for that

after update to the newest version
1) Extragroup for Steamregistered User doesn't work. They in the Group unconfirmed User
2) As an adminuser that is in first Group (registered user) and secondary Group (Administrator)
you canot Link to the Steam Account. It says successfully link, but in Adminarea no steam ID is under the User.
3) As an Adminuser in first group(Administrator) you can link to Steam
I will test with a User in one Usergroup... (Stay tuned:-) )
and the winner is

You cannont Link to an existant account .
Vbulletin 4.1.10 Suite
Steam Connect 1.3.2 RC1