I fiddled around a bit with it. Its cool and if I can think of any implementations that need it then I'll use it but I think sometimes people use it just for the sake of using it.
Also IE has a really bad implementation of the DOM.
Done Frihost support it? I know it dosn't support DOM in PHP.... well not the part I need anyway
I would recommend using prototype.js if you want to do AJAX as it wraps it up quite nicely. Moo.fx is my recomended visual effects libary.