I did an aptitude safe-upgrade today and was pleasantly surprised to see that KDE 4.4.3 was finally in unstable. The only problem I had with the upgrade was that I got a black screen when I tried to re-login to KDE.
I didn't find much on Google or Debian lists but this post on KDE gave me an indication and I checked the status of the package plasma-desktop. dpkg told it was uninstalled at some point. I installed it using aptitude and lo-and-behold, I was able to login the new version of KDE.