We're not 100% convinced of the safety of his approach, but Kevin Miller's determination to recover his lost iPhone -- combined with the power of MobileMe's new Find My iPhone feature -- led him on a wild chase across Chicago, which he visited while he was attending a LEGO convention in nearby Wheeling, IL.
After leaving his phone in a bar, Kevin tried to get FMI working (via a friend's laptop & broadband adapter, ironically from Sprint; as Megan & Michael pointed out, you can't access the MobileMe page from the iPhone browser anyway) with no luck. The next morning, however, the phone began responding and Kevin's three-man team began the hunt. With laptop in hand and a succession of more and more specific location details, the guys began tracking down the errant phone.
We won't spoil the end of the story for you; Kevin's post is quite entertaining and worth a read. Still, once you do know how the plot turns out you may want to consider enlisting the police for a missing phone, rather than choosing to use their methods.