Apple was finally granted a patent, for which it first applied in 1999, on the user interface construction that has come to be called the "dock".

The patent calls it "a userbar" but Apple's own documentation calls it a dock (this image also comes from Apple's site) and that's the term it's generally come to be called. Including all the multitude of reimplementations of the concept. I'm aware of dock implementations for Windows and for Flash applications and there are probably others. Yahoo even has a "widget dock" (on which it has a patent).

Not everyone loves the dock, though. Ex-Apple human-interface guru Bruce Tognazzini published a column way back in 2001 harshing on the dock's (lack of) usability. Still, the widget remains fairly common in a lot of interfaces. The question is whether that'll still be true after Apple decides what it wants to do with this patent.

Given the early filing date it's not going to be trivial to find prior art if people want to challenge this patent. The amount of non-patent prior art cited is small, but there are an impressive number of related patents cited. (Including, to my great surprise, my own patent.) Scanning those it appears that Apple has at least touched on all the related work I can recall from back then.