Leaki, acorn was first but it's irrelevant anyway. The argument, like mentioned in the article, isn't who first used a square window with icons that launch programs on it first but whether the argument of whether the dock is a "rip off" of the Mac which is patently false.
IBM OS/2 LaunchPad:
Now is anyone going to seriously argue that the Dell dock is more similar to say the Next dock than it is to say the IBM LaunchPad?
The reality is, Stardock's been making these "docks" continuously for over a decade, long before Apple had for sure. It certainly wasn't inspired or taken from the Mac obviously and saying the the Next dock is even remotely similar is even more of a stretch than arguing that desktop accessories were the inspiration for widgets.
There are people outside of Apple Computer who have ideas on how the desktop should work and sometimes their ideas are similar to what Apple has done and sometimes Apples ideas are similar to what others have done. It doesn't mean everyone is ripping each other off.