I wrote the date in the upper right corner, you can see the time at the top, and put a circle around the spot where my house is. The blue dot marks the GPS spot.
So ... either one of these blue dots should be exactly at my house and the iPhone is very wrong, or all these blue positions are wrong and the satellites do something weird or are too far away from this city.
Update August 2010: since all iPhone3G updates and now my iPhone4, GPS works fine again.