D6 radically changes the way core translations are done, including how things are named, and where they're laid out. The packaging scripts on d.o have to be modified to take this into account, and Gabor and myself have already started discussing the required changes [1].
Until that's done (and we'll definitely let you know when it is), please do *NOT* attempt to tag an official release of your core translations for D6. It's not going to work anyway[2], and will just create more work for us and more hassle for you. Besides, RC2 is going to break a handful of strings, so you're going to have to re-do your existing translations a little bit, anyway...
Thanks, -Derek (dww)
[1] http://drupal.org/node/207401 [2] http://drupal.org/node/208454
p.s. cross posting from the devel list.