I also see in my ZD's dashboard log entries, something like:
2013/11/21 07:54:11 Low guest AP[AP-14194] radio [11a/n] detects User[guest] in WLAN[P-Net] roams from AP[AP-14194]
2013/11/21 07:54:11 Low guest AP[AP-14194] radio [11g/n] detects User[guest] in WLAN[P-Net] roams out to AP[AP-14194]