whohas

whohas is a command line tool that allows querying several package lists at once - currently supported are Arch, Debian, Fedora, Gentoo, Mandriva, openSUSE, Slackware (and linuxpackages.net), Source Mage, Ubuntu, FreeBSD, NetBSD, OpenBSD, Fink, MacPorts and Cygwin. whohas is written in Perl and was designed to help package maintainers find ebuilds, pkgbuilds and similar package definitions from other distributions to learn from.