Of course there are other translation projects beside the GTP and we try to cooperate and work together with them:
The Translation Project (or TP for short) aims to get the maintainers of free software packages, benevolent translators (why not you!), and users all together, so that computers and systems (like Linux or GNU) gradually become able to speak many languages.
The GDP is writing the documentation for GNOME and thus we work hand in hand with them to provide the GNOME community with documentation in their native language.
Our sister project, only translating the K Desktop Environment instead of GNOME.