An automated way to track bug reports and change requests is a necessity when a project goes public, or, for administrators, when your organization gets big enough that they can't just pop their head above the cubical and say "Hey, something's broken!"
Gnats is mostly driven by email. send-pr is used to generate problem reports, edit-pr updates them, and query-pr queries the database.
query-pr can search using regular expressions.
You can enable querying the database via mail. Place the arguments in the Subject field, and mail it to an alias that feeds it to query-pr.
Because of, I guess, an attempt to make the current version backwards compatible, a number of variables hardcoded into files are read from the currently installed GNATS. To get around this, you should hand install /usr/local/share/gnats/gnats-db/gnats-adm/config and tailor it before doing a configure, or, at least make sure you re-build and re-install when you're finished getting it to work.
There are a few files to setup in GNATS-ROOT (usually /usr/local/share/gnats/gnats-db/gnats-adm).