mupen64plus has changed its internal structure slightly with its upcoming release featuring the new API 2.0. Beside the most obvious change for the user - the removal of a graphical interface as part of the core distribution, there will be an explosion of packages provided by debian.
mupen64plus in Debian
mupen64plus was accepted by ftp-masters and will hit the archives soon. The debian package needed some adjustments to be accepted. This means that glN64 had to be removed because it is not distributed under a dfsg compliant license. If anyone knows Orkin then please ask him to contact the mupen64plus team.