Smartphone Radar works great for me but I was wondering if using Bonjour might be another way to detect iPhones. I am not a programmer but I found pybonjour (http://code.google.com/p/pybonjour/). It is a python library that listens for Bonjour service announcements. I ran their example and observed the iPhone announces a service type of _apple-mobdev2._tcp. My iPhone broadcasts this at least every 10 minutes or so, sometimes much more often. Just a thought if someone that knows how to program was looking for a direct signal from the iPhone instead of proxy methods via log files.
example output:
fullname = e0:c9:ba:7c:71:c9@fe80::d2b9:baff:fe9c:73c9._apple-mobdev2._tcp.local.
hosttarget = iPhone5.local.
port = 62078