In December 2004, we found PhotoPass photographers were often where the characters were. We found them at:
Epcot - for group shots with SSE in the background and at France with Sleeping Beauty, in the UK with Pooh and friends and with Mary Poppins and in China with Mulan. They were also there when the "character bus" came around but since this has been replaced with the Character Connection, I would imagine the PhotoPass folks would be in there.
MGM - near the "Giant Hat" for group shots, just inside the entrance when the characters were out, with Sourcerer Mickey, at Al's Toy Barn with the Toy Story Crew and at the Star Trailers (Donald and Daisy were at one and JoJo and Goliath were at the other when we were there).
AK - near the tree for group shots and at the character trails in Camp Minnie-Mickey.