Short overview (for news sites)
This release includes lightweight user space priority inheritance support (http://lwn.net/Articles/178253/), a "lock validator" debugging tool (http://lwn.net/Articles/185666/), a new power saving policy for multicore systems, SMPnice (http://lwn.net/Articles/186438/), a much improved SATA layer (http://lwn.net/Articles/183734/), swapless page migration (http://lwn.net/Articles/160201/), per-zone VM counters, per-task delay accounting, a new per-packet access control for SELinux called 'secmark' (http://james-morris.livejournal.com/11010.html), randomized i386 vDSO, a few new drivers, additional device support for many existing drivers, many bug fixes and many other small improvements.
Important things (AKA: ''the cool stuff'')