Found extremely useful and perfectly designed AJAX file upload script. It doesn't reload page (uses dynamic JS iframe creation/manipulation) and very easy to implement even for entry-level JS programmer (as I am).
http://wiisit.com/upload2.zip (1kb)
P.S. script is slightly modified to expose $_FILES variables inside PHP though you can find link to original version in copyright notice.
P.P.S. I can't handle the archive for too long - please - anyone - place it on long-term hosting and post it here.