For all those who want to submit publications to the IEEE and who are using matplotlib with the "usetex" option,
The IEEE require all fonts to be embedded (see http://18.104.22.168/pdfexpress/frhelpnologin.asp and http://ras.papercept.net/conferences/support/pdftips.php). Matplotlib unfortunately does not embed all the fonts into it's EPS figures.
The quick way to get matplotlib to embed all fonts into the EPS figures (instead of using PNGs) is to:
1) open "backend_ps.py" and "texmanager.py"
2) search for "dvips -q"
3) and add "-j0 -Ppdf -Pdownload35 -G0" just after the "-q" (see http://mpa.itc.it/markus/highres_pdf.html)