[Greasemonkey] GM_xmlhttpRequest: Anyway to tell what 'url' resolved to?

[Paul Bardo]

If I run a GM_xmlhttpRequest to example.com, but example.com redirects to
www.example.com is there anyway to tell?

If I try to go to www.example.com/example?a=100, and it redirects to
www.othersite.com/archive.html#100 is there anyway to tell that (whole
different domain)?

The request still works, and the responseText is correct, but I can't find
anyway of telling what the "real" url is.  I've tries looking at the
responceHeaders, but I didn't see anything there that would help.