It appears that this problem is more widespread than just this one user and is not limited to Windows Mobile devices. In fact the symptoms look just like the ones outlined in
bug 22808.
I have users on Mac OS 10.5.4 sending meeting invites to Windows users and they are showing up an hour later than was scheduled. Ical and Zimbra (NE 5.0.6) do not appear to be using the same timezone for the Phoenix, AZ timezone.
Any ideas?
-Justin