From the post you linked to:
There are two missing pieces though:
It's not particularly functional for Stack Overflow, because there's no way to create per-tag events. Apart from things like Meetups and major cleanup efforts, there aren't a lot of events that are worth intruding on every single reader's view.
The best part - scheduled events - is moderator-only.
There were two stages planned for the implementation of that feature: the first stage (which would suffice for nearly all sites on the network) was a fairly light-weight event-and-meta view driven mostly by meta-votes and direct moderator intervention. The second stage - making it functional for Stack Overflow - required deeper integration with the site itself and the (generally tag/topic-focused) communities on it. Sadly, this latter part was never finished and eventually ended up blocked by a larger project which could/should/may integrate with it in some form.
For the time being, you'll see the board pop up on SO (and MSO) occasionally when there's a blog post or (rarely) when a moderator or team member adds an "event" to the schedule.