The locations in the photos are only as good as the GPS / cell triangulation, and one of my photos from a wedding in Cambridge showed up down the road in Bury St. Edmunds. It's a shame the iPhone doesn't let you see and edit the location data for a particular photo (e.g. replace location information for one photo with location information copied from another). Perhaps iPhoto and/or Aperture support this, or at least allow you to edit the raw GPS coordinates. I'll see what tools are available.
Suboptimal, but cool nevertheless! I'm easily excited by such things, so I reckon iOS 4 was worth the installation pain.