The first update from Ghost about ActivityPub has a screenshot of their early experiment. There’s also a lot about timing:

In 2024, for the first time, it finally feels like we have a critical mass of people and platforms who are interested in rewilding the internet to bring back what we lost, and create something new.

Not sure about “for the first time”, but that’s a minor nitpick, mostly selfish on my part. I’m glad Ghost is doing this and look forward to following their email series.