Can’t say that I’ve noticed any US ads, but then since I use an AirCard from Sprint, my IP address consistently shows me as being in various locations around MCI, even though I could be in any other place in the country.
I only mention this because when I travel outside the States, and buy WiFi access locally, I notice all kinds of different ads targeted to the market I’m in.
If US was smart, and going after the business traveler, they would turn off the regional filters so people like me that travel with wireless access cards from cellular companies would see this advertising.