(This post is a rough copy of an email I sent to the mailing list.)
I wanted to remind the community that currently all WHATWG standards are being developed on GitHub. This enables everyone to directly change standards through pull requests and start topic-based discussion through issues.
GitHub is especially useful now that the WHATWG covers many more topics than “just” HTML, and using it has already enabled many folks to contribute who likely would not have otherwise. To facilitate participation by everyone, some of us have started identifying relative-easy-to-do issues across our GitHub repositories with the label “good first bug”. (See also good first bugs on Bugzilla. New issues go to GitHub, but some old ones are still on Bugzilla.) And we will also continue to help out with any questions on #whatwg IRC.
You should be able to find the relevant GitHub repository easily from the top of each standard the WHATWG publishes. Once you have a GitHub account, you can follow the development of a single standard using the “Watch” feature.
There are no plans to decommission the mailing list — but as you might have noticed, new technical discussion there has become increasingly rare. The mailing list is still a good place to discuss new standards, overarching design decisions, and more generally as a place to announce (new) things.
When there’s a concrete proposal or issue at hand, GitHub is often a better forum. IRC also continues to be used for a lot of day-to-day communications, support, and quick questions.