With the controllable jQuery Progress Bar, writing a form upload progress bar seems like a piece of cake now. Hypothetically, all we need is to create the bar, poll for the progress of the file upload, derive the new progress bar value (in percentage) and set it.
To do that you need to prepare the php script to do it. By default PHP cant report the progress of upload progress. However people smarter than me have already solved that problem. In 5 mins i’ve found 2 solutions: the Alternative PHP Cache (APC) method as well as the UploadProgress method. Both of them are PECL packages. Because i couldnt get APC to work on my server properly, i’ll document the UploadProgress more in detail here...