I overhead the conversation yesterday that the file upload on the mac was not working or rather the
FileReference onComplete was not being fired. Today, Abdul Qabiz finally confirmed the bug. He also eventually found the fix for the same. The fix was to send an empty response from the server side upload script.
Read Abdul’s article for the details – Workaround: FileReference onComplete is not fired on Mac OS.
The bug is supposedly fixed in Flash Player 9.