Non-Americanised English date formats
Discourse (finally) supports International English date formats, which you can enable like so:
- Head to the “Interface” tab in your preferences
- Set “Interface Language” to “English”:
- Click “Save Changes” at the bottom of the page
Don’t worry, this will just update dates from M-D-Y format to D-M-Y, but won’t change every occurrence of “z” in Discourse’s interface to an “s”, or insert "u"s in seemingly-arbitrary places… not yet at least 
Like/Watch/Track/Mute topics via email
For those users who prefer interacting with Discourse via email, various post actions can now be carried out with simple email commands. As with all email-related functionality, this is documented in our FAQs:
Tell users when they attempt to log in with a secondary email
For users who have many email addresses associated with their Discourse account, it can be hard to keep track of the primary address, which is the only one which can be used to log in. Now when logging in with a secondary email a much more useful error page is displayed, telling a user which email address they should log in with instead.
Bugfix: seemingly-random logouts
A number of users reported this issue to me (and many more were affected), where Discourse would seemingly randomly log you out across all your devices. This has now been fixed with a much more resilient method of storing data for a user’s sessions.
Full technical details can be seen in the issue, particularly including where I finally figured what was going wrong. (Sometimes staring out the window can be productive!)
Many thanks to @mkohler and @lissyx (and all other users who were affected) for bearing with me while I fixed this.