Om Malik, a technology blogger that is respected by just about everybody, notes that several sources report that Google is seeking bids to build what just could be a national broadband network over which Google content could travel.
And along with that content, Google- by owning the network - could determine what packets go where, and then target local advertising for specific destinations.
Now, here's something I just thought of. Presumably, the "dark fiber" that Google is said to be shopping for could also be the conduit for a souped-up, VoIP component to Google Talk. You sign up for Google Talk and your calls go over the Google network. Then based on the locality or number you are calling, Google Talk's interface could show you display ads for that area.
Let's just say I am a golf resort marketer. Incoming calls placed to my number via Google Talk could show Google AdWords for my resort, for golf clubs, for area attractions.