Mariano: Sadly, I do not even know anyone who speaks Quechua, but I am sure someone does, and there must be a rather important Quechua community, for otherwise Microsoft would not mind doing a translation, so I am sure there must be people who both speak Quechua and are willing to work on translating GNOME...
Coincidentally (or not?), someone sent a mail about starting Quechua team to gnome-i18n list just yesterday. Guess you'd like to know about it.
We at the GTP always hope that means another supported language in Gnome :)