Are you sure Google guessed in Example 3? It usually does the "leave now to get there on time" for every event in your calendar (for which it can find some kind of geographical reference, fitting or not).
Google had picked a location for me and called it "work" which was not the exact street address but close enough. I know I didn't ever key in an address and explicitly tell them it was where I work, or else they'd have had the correct address from the get-go.
Finally! We can replace the old cliche where a girl has basically moved in with a guy once she has a toothbrush at his place, by a new one, where she has moved in once her phone calls his place home.
Edit: Just checked, it now thinks I work at my kid's school.
Aggregated data from a number of different sources can give a near-complete picture on a customer.
The reason I think this is the case is that it kept on updating my "home" while I took a road trip across the East Coast. So when I moved from NYC to D.C. everyday it would tell me the commute to NYC (Home) because I had spent a few days there and Google thought I was based there.