I happened to install KNetworkManager over my default installation of KUBUNTU 11.04. Then I tried to open if from the K_Menu-System-. I got a message asking me if want to use it always. I replied yes. After a reboot, the interface of the tray icon of network manager changed, though the functionality appears to be same.
I didn't like the interface. So I uninstalled KNetworkManager. BOOM I had no network manager in the system tray. I uninstalled and reinstalled 'network-manager-pptp-kde' but I could not get back the interface that I liked.