It's actually becoming apparent that why Kubuntu team "invented" this package manager because the current package manager GUI when compared with the Ubuntu Software Center ... well it does lack few "user-friendliness" and like the Synaptic (although it's most certainly rich in features and the best option for the power users) the current package manager is not optimized for the touch-sensitive devices or the "future" in general.
So in hope for a more user-friendly package manager GUI they came up with the one called Muon. Soon after the initial announcement, they actually made available the 1.2 beta version few weeks ago for testing which you can install via their PPA channel.
The latest news is that few hours ago they've released the latest version of Muon, 1.2 Beta 2!. And according to the developer this won't give new features but seems to carry bug-fixes only. So if you've been using the older 1.2 Beta version, then it's advised to upgrade to this version.
If you have never installed it before, then you can install the Muon 1.2 beta 2 in Kubuntu 11.04 Natty Narwhal by using the below command in your GNU/Linux Terminal window.
sudo add-apt-repository ppa:echidnaman/qapt-experimental
sudo apt-get update
sudo apt-get install muon