dmikov, while technically true that Apple bought the operating system which became Mac OS X, it's important to note the NeXT was founded by Steve Jobs when he left Apple, that Apple was initially quite upset about some of the talent which he was taking w/ him, and that the result of the buy-out has often been described as an internal takeover of Apple by NeXT.
Also, as much as I wish it were, Mac OS X is not purely NeXTstep (in particular, I miss Display PostScript; top level Print, Hide, Quit and Services menus; the vertical menubar; repositionable tear off menus; the pop-up main menu, &c.) and for various reasons, (most notably Adobe's reneging on providing a free license for Display PostScript) required a great deal of coding on Apple's part (much of which was done by ex-NeXT employees which Apple gained in the buyout).
There're also a number of innovative Apple technologies:
- TrueType (Apple's Royal font format was traded w/ Microsoft to get TrueImage, MS's PostScript clone)
- Apple Advanced Typography / QuickDraw/GX
- QuickTime
- HyperCard
- AppleScript
They were rated the most innovative technology company in 2008 by Businessweek after all:
http://images.businessweek.com/ss/08.../index_01.htme
William