[igraph] error when plotting igraph

[Jack]

Hi list,

I have a probably very basic but common question on plotting a graph.
I install python-igraph using this (in Ubuntu 12.10)

$ sudo add-apt-repository ppa:igraph/ppa
$ sudo apt-get update
$ sudo apt-get install python-igraph

then I know somehow I need Cairo to plot. Therefore, I did the following:

$ sudo apt-get install libigraph0 libigraph
$ sudo apt-get install libcairo2 libcairo2-dev
$ sudo apt-get install python-cairo

then in python, I did:
 from igraph import *
 g = Graph.Famous("petersen")
 plot(g)

and it told me:
 "NotImplementedError: showing plots is not implemented on this platform: Linux"

Am I missing something during the installation? How to correctly install
Cairo in Ubuntu?
Thanks in advance.