I have a Dell XPS L401x and just installed 12.04. I have a mini-display and an HDMI output, and I could hook up two Dell UltraSharp monitors to each port on Windows 7, and get a triple monitor setup.
Doing a bit of research, it seems like the mini-display is wired to the integrated graphics card whereas HDMI is hooked up to Nvidia graphics card. I've also installed Bumblebee as it seemed like that was the proper way of installing Nvidia drivers on Ubuntu.
At the moment none of my monitors is being recognized by Ubuntu. Is it even possible to have a triple monitor (laptop display + 2 external) setup? Has anyone successfully done this?