When building WordPress themes from scratch it is easy to forget about things that “just work”.  One of such things, often forgotten by newcomers to WordPress theme development, is trackback auto-discovery - a really tiny bit of code, which is not visible to a naked eye (an eye without HTML source that is).  Trackback auto-discovery provides a specially formatted HTML code for other content management systems to find a trackback URL in your post.  Gladly, there is a Codex page that covers trackback_rdf() function.

If you don’t have a lot of time to follow WordPress development news, just read to this one blog - WordPress weekly digest.  One short post per week, with a summary list of what changes went into trunk.  Occasionally, there are also brief explanations like this one:

 The last change means that the next time you login the value stored in the database will change - this means that if you do upgrade passed this point reverting back to an old version will invalidate all users passwords and they will need reseting. Therefore it is a good idea to backup up your users table before updating to the latest trunk.