You can use ipython to do this, for instance the command:
ipython nbconvert notebookname.ipynb --to latex --post pdf
to convert notebookname.ipynb to a pdf. It does however require that you are running the latest version of texlive (that's texlive 2013) to have the supporting software. Note that Ubuntu 12.04 comes with texlive 2009 from their repositories. 2013 can be installed from CTAN directly, just follow these directions. Then you are up and running, and it looks great.