The first pitch I ever heard for Beagle was 'it's like searchlight', so I always assumed it came later- but I looked it up, and it's hard to tell. inotify 0.8 was announced about a month after Steve Jobs started advertising spotlight, and Beagle grew out of Dashboard which certainly has design documents that indicate they wanted to do that. So... I think you might be right.
Funny. Apple takes features from other OSes like Linux. Linux in turn takes features prominent in Apple's marketing strategy for OS X and replicate it in their own.
Docks of one sort or another have been around for years. RISC OS had a dock-like icon bar in 1987, GNUStep nicked one from NeXTStep in 1994, and I'm sure there are earlier examples.