With more recent talk about namespaces in PHP 5.3, bloggers all over are tossing their comments into the discussion. Chris Hartjes is one of the latest with his thoughts on the point of the functionality.
I'm an outsider when it comes to tracking the going-on in the world of PHP internals. So, because of that, I'm not going to comment on the actual syntax of how namespaces will be implemented or it's impact on internals. That's not really important as far as this particular discussion goes.
He mentions one of the primary arguments for namespaces from the casual developer's perspective - keeping things separate and so classes can have the same naming as some of their cousins in other namespaces.