Hmm, not sure how to help on this one...
Did the installation run without hitch? Did you select Workbench: as the default partition to install the OS on?
I hope I'm not being insulting to your intelligence/experience because you certainly don't sound like a newbie but it's all I can think of...
Try running the install again, but select the "Expert User" option and check the directories where the OS update is being installed.
Good luck
