In the interest of being more agile, we're trying to do a better job of keeping our thinking about active feature development separate from exactly which release vehicle we're going to use to get it into the hands of users. As much as possible, we'll be trying to develop these changes in add-ons for feedback rather than in the core.
To that end, some (but probably not yet all) of the work we expect to be active in the coming months includes:
- Mail account provisioning: surveys from a number of users have communicated to us that lots of people who download Thunderbird both want and expect to get an email address as part of that. We're prototyping some UI around that
- Themes: we'd like to have at least basic lightweight theming exposed to users from the core, without having to even install a special addon.
- Backend changes to support the sync (formerly known as Weave) add-on
- Important add-on hooks; mostly (but not only) ones that are justified by existing addons that need them.
- Some of the stuff from https://wiki.mozilla.org/Thunderbird:Thunderbird_Post_3.1_BackendPlans.