Mike, if what you have floating in your pond is FA (filamentous algae) of some sort, it is on it's dying/decaying portion of it's cycle and will be sinking soon. That stuff tends to start it's life by growing on the bottom. Once it starts to fade away it begins to decay and the gasses will get trapped in the tangles and float it to the surface.

It would be best to rake it out and compost it or dispose of it somewhere so that it's nutrients don't wash back into the pond.

The following link will take you to a thread that is in the "Common Pond Q&A" section and will give you plenty of reading on the subject...

http://forums.pondboss.com/ubbthreads.php?ubb=showflat&Number=92633#Post92633

Since photo bucket changed their rules regarding the sharing of photo, the above link will be missing a lot of pictures, but there is still plenty of learning available in the text.

Fish on!,
Noel