<i>Have they given back to BSD?</i><p>Yes.<p>Grand Central Dispatch, one of the major new technologies in SnowLeopard, was open sourced and is already implemented in FreeBSD. See here for more: <a href="http://www.osnews.com/story/22331/FreeBSD_Gets_Grand_Central_Dispatch_Port" rel="nofollow">http://www.osnews.com/story/22331/FreeBSD_Gets_Grand_Central...</a>