After updating Exchange 2010 to Service Pack 1, I had a repeat of my previous problem.  Turns out, I had to repeat the process for exppw.dll .  Only this time, I made a typo in the applicationHost.config file, resulting in numerous errors in the Application event log:

The worker process for application pool ‘CitrixWebInterface5.3.0AppPool’ encountered an error ‘Configuration file is not well-formed XML’ trying to read configuration data from file ‘\\?\C:\inetpub\temp\apppools\CitrixWebInterface5.3.0AppPool.config’, line number ‘3’.  The data field contains the error code.

After finding the typo (a missing space) and restarting IIS again, everything was fine.