After upgrading to Jaunty (Kubuntu 9.04), I lost network connectivity on my laptop. I noticed KNetworkmanager had disappeared from both the panel and the menu's. However you can still start it manually. Just type in knetworkmanager in a Konsole window. You can put it back into the menu, using the menu editor. Just right-click on the K-menu.
Appearently, it was removed from the menu's in favor of a new widget called plasma-widget-network-manager. However this new widget has a bug. See https://bugs.launchpad.net/ubuntu/+source/plasma-widget-network-manager/+bug/351628 for more info.
