Downloaded and installed latest versions of DOM + Uploadify, I'm getting warning messages in the js console saying that jquery isn't defined.
Upon looking at the source code, it looked like livequery was being loaded before jquery, triggering the problem. I then looked at the files for both DOM and Uploadify, and discovered that while the Uploadify FieldHolder function has the requirement call for jquery, the DOM constructor actually didn't have it at all!
So I fixed the problem by adding this in the DOM constructor right before all the other js scripts are loaded.
I'm not sure if UncleCheese omitted it for some reason or not, but please give me a heads up if adding this in breaks anything.