This has actually been a long time coming, and will be the canonical LSG. It's built into MediaWiki, supports live controls and code snippets, and uses OOjs UI. There's still a lot of stuff missing and neither design nor content are final.
With that said, we can do a better job proactively communicating the progress of this effort, deprecating old content, and keeping the wiki up-to-date. I would ask all members of the UX team to help with that.
Erik