Well, while testing my "new" Canon 300mm FD lens, it seems I managed to capture Pluto.
Two sessions, 24 hours apart.. and just a bit above and right of the centre of the frame, it is quite visible that one dot ( mag 14 ) changed the position..
This simply must be Pluto
And yes, it is Pluto.. I just confirmed it with CdC, the position and the amount and direction of shift is identical.
Both images (200% crops were used for this animation) were done with Canon 400D, ISO 1600, 300mm FD lens @f/6, stack of 15x20sec frames + darks.