Yep. Perplexing is a pretty good word for it. Unfortunately, who knows if we'll ever get an official explanation either. It's pretty cool though and I like it regardless. For some reason, seeing a map of my route makes me feel a bit more motivated to get out there and go for a run or bike ride. Also, as someone posted earlier, adding in Elevation stats is great. The Activity.app is really becoming a pretty great place to keep track of stuff.I'm perplexed too. Keep in mind a WiFi can be 'seen' and identified a lot farther away than it can be connected to. So you can 'see' WiFi's for a good distance. However this still doesn't seem to offer a full explanation.
Also to give an idea of the complexity here is DARPAS' synopsis page on non GPS tracking technologies under development.
http://www.darpa.mil/program/micro-technology-for-positioning-navigation-and-timing
Nice link by the way, definitely going to save that to read later.