In brief: Currently, a translation is released when it reaches 100%. There were a few ideas when to include and exclude a translation in a release (different for major, and minor). Some suggestions where to continue to release even if there's no 100%, and there's an active community of translator for a language. Rob suggested even to get an OK from the trans. community of each language.
Rules should be simple, though, as Jürgen Schmidt commented, since it cause effort to manage & track too many rules, in addition to manually build the translation releases each time. Andrea proposed a more flexible strategy, which emphasizes the importance of continuing the language support over versions (at least in minor releases), who may find it annoying, for example, that there was Hebrew support in AOO 3.3, but not in AOO 3.4 (grr@#$!!). + That's a strong point, TMHO. + In addition to Andrea's concern about being in touch with the community of translators, as a solution, maybe we should build a list of private emails. For example, I wonder if translators would prefer to add their private email to the cwiki page of volunteers, instead of just subscribing to the L10N list. This would allow the PMC to send important updates/requests directly to translators (e.g. a wake-up call, before a release). Tal