On Ubuntu 13.04, many of my
dvips calls deliver error messages like,
dvips: Font Helvetica used in file <...> is not in the mapping file.
All these calls work perfectly fine on Ubuntu 12.10 which I'm using in
parallel on my laptop.
gv can also display the 'missing' fonts if called
directly, so I guess they are installed correctly and it must be an issue with
dvips in Ubuntu 13.04