I've recently upgraded from iPhoto '08 to '11 and am in the process of cleaning up my geotagging. Most of my photos had been geotagged outside of iPhoto, but for a lot of them it wasn't as accurate as I'd like. So what I've done is flag all of the photos where I'd like to zero in a little more on the map. Working one at a time I can just select the photo and, in the info pane, drag the existing pin a little bit to a new location on the map. Works fine.
However, I have large swaths of photos which are all very nearly in the exact same spot (taken in the same room in a building, for example). When I highlight multiple photos, though, the map in the info pane doesn't let me drag the pin. (I'm guessing that the pin shown is for only a single photo, such as the first one selected.) Is there a way I can re-assign the place on the map for multiple photos?
Edit: Requested screen cap: