Comment 2 for bug 447241

I have found a solution (using the gnome network manager applet):

1. Add the line "deb http://ppa.launchpad.net/network-manager/trunk/ubuntu karmic main" to your /etc/apt/source.list
(sudo apt-key adv --recv-keys --keyserver keyserver.ubuntu.com [ID] - if you want to add the key for the PPA)
2. Update your package list
3. Install the package network-manager-gnome
4. Remove the packages plasma-widget-networkmanagement and plasma-widget-network-manager
5. Add "nm-applet" to your autostart
6. Verify with "nm-connection-editor" that the wired connections are set up correctly.
7. Edit or create your DSL connection (pay attention to NOT set "Available to all users" for this connection!).

It seems that DSL isn't added to the network manager plasma widget.
Perhaps it will be available at the next ubuntu release (10.04 "lucid").