ISS and Falcon 9
The ISS followed another orbiting object, it was a few minutes ahead, fainter and seemed to be travelling quicker.
I have really (over)worked this image to bring out the unknown object..
-- Update 14/06/12 --
It appears that this may be part of the Falcon 9 rocket which carried the Dragon capsule into Orbit. I will try a re-edit later with normal levels (rather than this image on steroids)
-- Update 14/06/12 @ 22:15 --
Updated the image with a slightly less enhancement to see the fainter Falcon 9 trail.Pretty happy with this one, despite the remaining noise..