The Thunderbird developers have also discussed the timing of the overall string freeze for the final Thunderbird 3 release. Our proposal is to freeze all strings for Thunderbird 3 on September 29 2009, giving localizers a minimum of 4 weeks time before the first release candidate (RC1).
Please note that this date is preliminary at this point and will be reviewed as we approach the beta4 release date. We could move it forward if we are happy with the strings at b4 or we could move it back a bit if really needed.
However, the 4 weeks timeframe to get your localization in shape will remain in place. So if we decide to move the string freeze date forward or backward, localizers will always have at least four weeks to work on their localization for Thunderbird 3 without any string changes.