well that is interesting - following Helge's lead, I took a geo tagged image that had been downloaded to my computer bye eye-fi but whoes location would not be recognized by aperture and extracted the GPS information with exiftool. I then used exiftool to put the information back and imported it into aperture. now aperture recognizes the info. I added one second to each longitiude and latitude to make sure I was actually doing something.
Here's what it looks like
[MosieriMAC:~] bmosier% exiftool -GPSLatitude -GPSLongitude IMG_0413.jpg
GPS Latitude : 35 deg 17' 52.00" N
GPS Longitude : 120 deg 39' 56.00" W
[MosieriMAC:~] bmosier% exiftool -GPSLatitude="35 deg 17' 51.00"" N" -GPSLongitude="120 deg 39' 57.00"" W" IMG_0413.jpg
Warning: [minor] Entries in ExifIFD were out of sequence. Fixed. - IMG_0413.jpg
1 image files updated
I don't know what the warning means - maybe that the GPS info and the IFD info are inconsistent.
But it now works in Aperture!!
Obviously the format of the file has been changed in someway that Aperture now likes - but I'm to tired to look at it more.
(actually I did a diff from the output of exiftool on the two files - the main difference seems to be order and a few blank lines. I think I would have to diff the actual files - but that would be a mess)