KDE 4.7 has been released just few days ago with many new features, updates, and applications. Read announcements
Kubuntu Backportshas added KDE 4.7 for Ubuntu 11.04 Natty release. So Ubuntu Natty user can update to KDE 4.7 with:
sudo apt-add-repository ppa:kubuntu-ppa/backports sudo apt-get update sudo apt-get upgrade
kubuntu-full package if you’re first time tring KDE on your Ubuntu.