Yes, all servers are on the same administrative group and all AD fields are populated the same. That said, I have not asked users on different Exchange servers to try using the lookup feature as a comparison. It could be this one problem Exchange server.
I've been using my own account for testing. If I colleague who's mailbox resides on my Toronto Exchange looks me up, they will see all my contact information (home, work, fax, PIN and e-mail addy). If a user in our Montreal Exchange looks me up, they only see my fax and PIN.
Steve A (Sys/BES Admin - Toronto)
BES Xpress + BES 5.03 on 6 Exchange 2007 servers across Canada,UK and NYC