After breaking my head against a wall trying to find any guru around that 'could' have done a good solution to this matter, I found a couple of interesting links such as the jqUploader JQuery plugin by lussumo (with a SWF object for upload), the tesUpload object (with a Perl script to get the bytes uploaded info) by Tomas, SWFUpload object (another flash object) and the closest one to what I am wondering about but requires PHP to be patched to make use of upload_progress_meter_get_info.
I wonder if it is possible to actually do what I am saying and if there is any solution out there that I missed on my googlexperience. I have seen some scripts around there that promise such solution but when I tried, poof!, it didn't work as expected. So the challenge is here... I am going to try a solution that actually checks the actual file size of a temporary file after an uploaded form has been posted... Anyone for the challenge? or anyone knows any 'guru' out there to get me to the right direction?