While probably no one else cares, I'll note this for myself so I'll have somewhere to look later.
Using gentoo, with the most recent muttprint and tetex. I was unable to use muttprint from another program, notably mutt. After debugging a but I realized, what was actually happening was that dvips was dying with an error like "dvips: ! couldn't open output pipe".
After a quick google search I learned dvips had a security problem with executing malicious code. So I was able to fix up muttprint to do the right thing.
