From the KDE 3.2 release:

• Working in concert with Apple Computer Inc.'s Safari web browser team, KDE's web support has seen huge performance boosts as well as increased compliance with widely accepted web standards

Now while companies giving back is nothing new (Apache, Linux kernel, et cetera) it's still a good thing to see. I remember there was a lot of suspicion towards the original post about Apple diving in to the code on the khtml list. I haven't been following the developer list, but it sounds like things are going well.