Lets be real: Most printers today follow one of a handful of standards. They can interpret Postscript, or PCL, or in some cases raw PDF files. CUPS is common driver/filter package that can convert between a few formats and direct the output to the proper port (be in /dev/lp1, /dev/sc01, or an IPort combo).

Most unix-based programs that have print functionality print in Postscript. MicroB is based on Mozilla, which has a PS generator. There are some nice wrapper scripts one can use to print text to PS printers with lots of formatting options. Support for this exists in debian, it's just been stripped from the version Maemo did to cut some fat out of the system.

I'd love to see this as a package users can install that's optional. I'd really prefer to see a universal PDF output generator too that can "print" (from MicroB and the like) to a PDF, which I can later print on a real computer later if I like, or edit with Xornal, etc. I don't think we'll ever see an OS-level universal interface for printing under unix of any flavor. But having the option of postscript or PDF output will solve the issue for 95% of the people out there. (And the other 5% can suck it up and buy a real printer...)