I installed TeX Live 2010 on my Mac in order to test this, but
mysteriously, the pdftex.map file does not have a line for pbkdo8y. The
closest match is
currently Ubuntu still uses Texlive 2009. I also got the same bug (http://article.gmane.org/gmane.comp.python.matplotlib.general/26110) with Texlive 2010 installed directly from tug.org.
I think it is unlikely that this is an Ubuntu specific problem, but I don't know for sure whether this file gets generated during the installation or is unmodified from the Texlive distribution.
I installed TeX Live 2010 on my Mac in order to test this, but
mysteriously, the pdftex.map file does not have a line for pbkdo8y. The
closest match is