Other big news in this release is the shift (at least for a few releases) to match Firefox release numbers, so it's jumping now from 31.7.0 up to 38.0.1. They note on the Release Notes that "There was no Thunderbird 38.0 release." but neglect to include that there was also no 37, 36, 35, 34, 33 or 32 release.

I'm just waiting for the naming convention to change over to randomly-chosen members of Canidae so we can be more like Apple.