I have updated all 2.4 translations that were sent to me. You can download them from the language packs section.
If you have additional up-to-date language packs, please contact me directly.
If you want to create a new one, you're welcome to do so. You might want to use an existing language pack from a previous version as a start base though. It's up to you...
Finally, language packs in 3.0 will be essentially the same except that they will include definitions for the locales they can serve in a small file called for example
fr-FR.locale.php. (A 3.0 language pack can actually define several locales at ounce by including several such files.) Those files will be detected by b2evolution and imported automatically.
This should make it even easier for users to install new locales. All they'd need to do is copy the files into the locales folder and then enable the desired locale from Global Settings > Regional.