http://www.mugglenet.com/editorials/theburrow/edit-anelson01.shtml

A very well written opinon. Not only does it not reveal anything we do not already know, it is well written, and makes a lot of sense.

Okay, I personally believe this to be the most plausible theory I have read. As such I kind of regret reading it, it almost seems like spoiling the ending to a great series. My dearest hope is that it is wrong.
Here it is
http://www.redhen-publications.com/Changeling.html
read at your own risk. It is lengthy...