The Nest?

While sitting on that lovely little indoor invention someone created so we don't have to go outside to the outhouse, I spied out the window what I believe was a young bald eagle flying by. (11:40 AM - Nov. 29, 2006 - Overcast - TV says it is 57 degrees out.) He or She had a bit of brown on his/her head. Not completely stark white. The eagle was heading down stream crusing the creek.
So I ran out hoping the bird would settle somewhere where I could get a picture but no luck. Well that is to say no sightings of the bird, but I did notice this, now that all the leaves are gone. A very large nest. Do I dare speculate? I will be watching! Though it is possible that this is the home of the our local Great Blue Heron?
PS - 12/19/06 - My latest thought is that this is a squirrels nest, though it is an odd place on the edge of the water on the island like that.