With the latest ipython one can run ipython nbconvert latex mynotebook.ipynb. The latest ipython can currently be installed from https://github.com/ipython/ipython, at the time of this writing this is the 1.0 development stream.
ipython nbconvert latex mynotebook.ipynb will result in a latex file. texi2pdf should then be able to convert this tex file into a viewable pdf - in my case I had to manually copy all the files and images out of the associated mynotebook_files directory to the same directory as the .tex file, both of which were generated by ipython nbconvert. If you encounter latex errors, see http://www.tug.org/texlive/acquire-netinstall.html for installation instructions for the latest latex. The default Ubuntu texlive package (as of 13.04 at least) is not recent enough to perform the conversion!