This current tirade stems from implementing a file upload progress meter in PHP5. Yes, PHP5.2 has some hook, and there's a PECL extension. [...] I realize this is partially a PHP issue I'm ranting about, but it's ultimately a hacky workaround to a basic piece of functionality that browsers should support.

He mentions an example where he basically directly asked a member of the IE team about it. It wasn't greeted seriously and still hasn't managed to be included in most of the popular browsers of today.