jQuery won't automagically fix the fact that he's trying to base his submission on the results of an asynchronous request.
What you can do is the following:
1) Set the form onsubmit to simply call snappyajaxfunction();
2) In stateChanged, if the readystate is 4, obtain a reference to the form and do the following:
form.onsubmit = function() { return true; };
form.submit();
Basically - Set the onsubmit to always return true and then force it to submit again. For added usability you may want to disable the button causing the submission while waiting for statechanged to happen. And then re-enable it.
