UTM and MGRS to Latitude/Longitude conversion source-code?

Question

What open-source / public domain software is there "out there" for conversion between Latitude/Longitude, UTM (Universal Transform Mercator) and MGRS (Military Grid Reference System)? We're using a VB6 library at the moment and would prefer to use something in another language and with a longer pedigree.

Answer 1

PROJ.4; I don't know if it does MGRS, but I seem to recall that it did Lat/Lon -> UTM when I last used it.

Answer 2

Have a look at this question and this question.