What normal person would want their friends to know their *exact* location? Google, I gotta be honest -- I don't get the spin. There are certain things I prefer NOT to know about my friends; among them are how many topless bars guys frequent or the number of times Dre goes for laser hair removal. Plus, there are plenty of other markets ripe for exploitation. For instance:
1. People who don't trust their spouse / partner / boyfriend / etc.
2. Parents who don't trust their kids
3. Paranoid people, in general
4. The mafia
5. Karl Rove. (Yes, he qualifies as a market segment. All by himself.)
I'm no expert, Google, so take my suggestions for what they're worth. Oh, and I totally signed up.