With the implementation of the Rapid Release development process for Thunderbird, I will no longer be announcing Thunderbird releases (now done on DevNews instead) as well as their changes in a blogpost, since any significant bugfix or new feature will, in all high probability, make it to the next release train within a few weeks. Calendar might be an exception till it joins the Rapid Release process.
The Rumbling Edge will continue to track comm-central landings every few weeks or so, as well as for Calendar.
Thunderbird release changelogs have been continuously updated since 2005, and the first version on that list was 0.7.3. (Thunderbird has come a long way, a journey of ups and downs indeed!) This list will occasionally be updated as well.
Compare this to old days when new releases would only come out “when it’s done”. How times have changed!