In Wireless/Clients/Client Events I get a list of events, including type (auth, roam, registration, de-registration, state change, active) MAC/IP/username, AP name, BSSID/SSID, location (!), RSS, auth state. I can't work out how to view much of this data for a particular client except by searching for them in this view - I'd expect it to be in the Client PortView. Ahh, I just found it - you have to right click on the client in the PortView and there's a Client Event History option.