I received confirmation that the lens is the 800 f/5.6L IS. The shot was taken with a 400 f/2.8L IS. Weird look to it though.
A comment on the last thread brought up this image of a Canon pro with an unidentified lens.
To me, It looks like the 800 5.6L IS. The problem is, it doesn't seem like the right size for it.
What do you think?
The image is from here: http://www.usa.canon.com/