I just ran across this blog post about getting NetworkManager to work under Dapper. This post mentions a couple of problems. The first has to do with an icon cache which prevents NetworkManager from even starting. I wasn’t having that problem. I was getting nm-applet in my “systray”. The next problem mentioned is that /etc/network/interfaces should only contain references to the lo interface. Oops. Guess that was modified somehow during the upgrade process. I guess this problems should only occur to people upgrading to Dapper from a previous Ubuntu. I would hope that a new install of NetworkManager would fix /etc/network/interfaces.