OK, there is an early version of the new upload system
here
This is the current map upload page with the upload progress plugin in place for the image and map file uploads.
It requires flash 9.0.45 or higher, and works with flash 10 too. If there is a problem with flash then the fields should degrade to a standard upload form (not sure if I've included that code yet actually...)
You can ignore all the text fields - all the form validation checks are disabled, and you do not need to fill in any required fields before pressing submit.
File uploads begin when you press submit.
The rest of the form is never actually submitted - that is disabled right now as it is just a test of file upload progress.
Any files you upload will not be saved. Once the uploads are finished and the bars are at 100%/upload says completed then that's it - nothing else will happen. Refresh the page to start again.