Of course shortly after posting I managed to track this down - we had changed the IP address of the library client as part of the upgrade and hadn't updated the server profile on the manager. What made this kind of tricky to track down was that library sharing does work, and the communication errors are logged only intermittently in the activity log.
2/20/2015 07:49:57 ANR0454E Session rejected by server GARUDA, reason: 201 - Communication Failure. Life is good now, my Friday is saved. -- -- Skylar Thompson (skyl...@u.washington.edu) -- Genome Sciences Department, System Administrator -- Foege Building S046, (206)-685-7354 -- University of Washington School of Medicine