For many packages that make use of the Translation Project, the copyright on the translations should be disclaimed by the translators before these translations are accepted for inclusion in the distributions.
A list of translators for whom the FSF has received and processed a disclaimer can be found on the authors page.
Some translators misread the translation disclaimer as an assignment of their translations to the FSF. This is not the case. The disclaimer merely says that the signer will never make use of the copyright on his or her translations: will never forbid copying them, and will never ask for some kind of compensation. This guarantees that the FSF (and everyone else) will always be allowed to freely distribute these translations. The FSF wishes to have this guarantee in a legally binding manner, to be on the safe side.
A translator usually disclaims all translations he or she could produce for any package. Yet the need for disclaimers is decided on a per package basis. When a package maintainer requires disclaimers, disclaimers are needed for that package for all translations coming from any team. For GNU packages, maintainers do not really have a choice, as the GNU project requires disclaimers for almost all its packages. For non-GNU packages, the choice is up to the package maintainer. The safest for translators is to fill out and submit the disclaimer form -- in this way they put themselves free, once and for all, to work on all translations they will feel like, whether GNU or not.
On the other hand, you may prefer to make legal arrangements other than the disclaimer below, e.g., for the sake of preserving copyleft protections on your translation. To do this, contact the package maintainer (and/or assign@gnu.org, if it's a GNU package), instead of sending in disclaimer form.