Little Snitch reported an outgoing connection from locationd which appears to be a new daemon installed by default on Snow Leopard.
A search for strings inside the locationd binary shows a link to http://skyhookwireless.com. The index of their page reads:
Skyhook Wireless' XPS is the world's first true hybrid positioning system.
Combining the unique benefits of GPS, Cell Tower triangulation and Wi-Fi Positioning, mobile consumers no longer have to wait minutes for a response or cope with inaccurate location.
If it happens again, I will report back with more details (endpoint, etc). I only clicked "allow once", so I did not create a firewall rule, unfortunately.