While we're growing very excited to see the KDE Plasma 2
tech preview release along with KDE Frameworks 5, which will hopefully be ready to try next month
, for now there is KDE SC 4.11.3 to play with. KDE 4.11.3 was released on Tuesday and should take care of more than 120 bugs.
KDE 4.11.3 is the latest monthly point release to 4.11 and has at least 120 known bug-fixes plus improvements to KWin, Dolphin, Kontact, Umbrello, and other KDE applications.
More details on KDE 4.11.3 can be found via the KDE.org release announcement
and info page