I’ve started using openSUSE Factory (next 12.3 due release is in March) which now ships with KDE 4.10 RC2 (4.9.97 more precisely).
I have to say it feels fast and smooth in almost all areas. The new bootsplash and desktop wallpapers are very cool and the overall desktop integration and decoration is very well integrated.
Kudos to both KDE and openSUSE communities. ;)
More info about the next openSUSE release: http://news.opensuse.org/2012/12/18/opensuse-12-3-milestone-2-released/
Awesomeness Of Openbox CLEAN by D-ARThwound
Every major mobile platform is now either using WebKit or will be soon. Except for one.