I just wanted to inform you that the Thunderbird team will release the
upcoming Thunderbird 3.1 alpha1 (codename Lanikai) milestone only in
English. The reason is mostly that we haven't been able to setup an
application target for TB 3.1 on the l10n dashboard yet. The fact, that
Firefox also doesn't release its first alpha in localized versions also
played into that decision.
Our next scheduled release, Thunderbird 3.1 beta1 is scheduled to be
released roughly one month from now. This release will be a fully
localized release. I hope you will hop on board then.