The 3D plotting facilities in matplotlib were recently (Aug 2008) removed because they had become unmaintained. I have taken the relevant files and started to update them so that they work with a recent matplotlib, or at least the matplotlib contained in Ubuntu Intrepid. They are still pretty broken but the plot3d command almost works now. I will continue to update them but feel free to send me any patches. You will need git to get the files via:
git clone http://jonathantaylor.ca/mplot3d.git cd mplot3d git pull