The question is does it give the memory back after the page is reloaded.  The case that I mentioned I fixed is an issue with IE and closures.  My fix addresses this.  However, I believe what you are referring to is not a memory leak per-se, rather just a byproduct of the way the javascript garbage collector works. 

I'd suggest looking at other popular implementations of AJAX and see how their memory consumption works.  Google Suggest, AJAX.NET Example

I will be blogging about the circular reference issue that I posted the fix in this thread for soon.  For some more information on IE and memory leaks see this article.