Comment 21 for bug 615902

My upgrade was unblocked after the following commands:

sudo aptitude install python-qt4
sudo dpkg -i --force-overwrite /var/cache/apt/archives/libqt4-help_4%3a4.7.0~beta2-0ubuntu3~lucid1~ppa4_amd64.deb
sudo aptitude install python-qt4

It removed qt4-assistant, installed libqt4-help and I was able to continue the upgrade with:

sudo aptitude update && sudo aptitude full-upgrade && sudo aptitude clean

After doing it, everything ran smoothly and I had KDE 4.5 installed

It asked about updating the file /etc/kde4/kdm/kdmrc

My two cents ;)