"Microsoft Location Finder" - how is it supposed to work

I have read a bunch on the net about Microsoft Location Finder
including Microsoft's "explanation" of how it works.

It determines your location, when it can, by accesing a uSoft
database of WiFI MAC addresses.

Is the database built into Microsoft Location Finder ?
I don't think so.

So what does it do, hijack someone's home WiFi for a few seconds
to interrogate the uSoft database and return the results ? That
doesn't sound kosher and obviously I'm not using my own wireless LAN
when I'm asking the question "where am I"

TIA to anyone who can answer this or point me to a discussion /
explanation of what's going on.

For others who are learning about Microsoft Location Finder from this
post, here are some links:

http://networks.silicon.com/mobile/0,39024665,39150711,00.htm

Go to http://virtualearth.msn.com/ and click on the "Microsoft
Location Finder" in the "Welcome" bar on the left.

Cheers, QE