I am a real newbie at matplotlib, so I apologize if this is an obvious question. 
I am running ipython in emacs and while the first time I use the show() command in the ipython buffer the graph shows up fine, subsequent times that I call the command it, the graph does not show up.  I am on ubuntu 10.04 (64) and I built the matplotlib library from source. 
I am trying to get the graphs to show up the subsequent times as well (sorry for the pun). 
Thanks for any help.

Ted Rosenbaum
Graduate Student
Department of Economics
Yale University