What is disk unmount watcher?

I can't explain exactly what it does, but it's part of the OS. It appears to be elated to networking (since it comes from the Kerberos stuff) and, uh, unmounting of disks. Are you having a problem with it?

Just speculation on the method, but it does what it says it does...

When you unplug a drive without ejecting, that process triggers the alert message about improperly removing it.

I have one too. When I hunted it down (by using activity monitor to sample the process) I found it in the private frameworks, in KerberosHelper/Helpers it is a unix executable file "open with terminal". It struck me as odd.