NiceRing,
If your IP phones are being handed DHCP addresses, then you can also open up WebPro and go to 15-01, and under the "ICM Extension" drop down menu, you'll see the extensions with the associated IP address next to them. If you don't have access to WebPro, and assuming you have a display phone you can simply go to the phone and hold down the "Help" button (About 2 seconds) Press 2 (for System Information) then press 1 (for Network Settings) press the down softkey to get to IP Address (DHCP) and there it is. (Again, assuming your IP phones are up and operational) Enjoy!
Thanks,
-Iron