this page seems out of date: http://wiki.openstreetmap.org/wiki/Mapnik:_Rendering_OSM_XML_data_directly
It looks like it was not updated when moving to mapnik2.
The main problem I had was to get the right mapnik2/python configuration on Ubuntu.
I was trying to install some packages named “mapnik2” but the correct installation required to add a new ppa and install “mapnik” packages rev2.2.0.
Since the example was not updated, I felt like none of the packages were working.