KDE 4 has been updated to 4.5.1 and should appear shortly in your Synaptic Software manager. In addition all 3rd party KDE applications have been updated and rebuilt against updated qt/kdelibs which should fix application relocate memory errors when launching various 3rd party KDE 4 applications.
KDE SC 4.5.1 brings a number of improvements:
* Stability issues in some of the platform components have been fixed, notably in the new shared data cache, in KHTML and in KNewStuff.
* Improvements to the ergonomics of moving applets inside Plasma panels.
* Listing of UPnP devices in the network:/ KIO slave has been fixed.
* KWin, the window and compositing manager has a regression fixed that would prevent desktop effects from being used.
* The weather and news applet now correctly update their data when the network connection comes back.
Full changelog located here.