Just a reminder - a friend of mine went through an hour of banding his head against the wall when a Spry example worked fine in IE6 and Firefox, but not the lovely IE7. Turned out that IE7 was being more demanding on the content type. He had forgotten to add:

IE7 decided that since the content type wasn't set right, it would just plain ignore the result. Awesome.

As a tip - this friend was using Model-Glue. When I do Ajax stuff in Model-Glue, I normally route all my events to an event handler just for XML events. This event works a lot like a normal "template" event, except this time the template is for XML. It basically does: