Ryan and Rachel have been doing an amazing job on this and it's very exciting to see it coming soon to core. Congratulations and thank you to them both (and all the other contributors).

I've just made a small plugin public that adds routes for bbPress post types, like Forums, Topics & Replies: https://github.com/thenbrent/BB-API

I've been using it for an internal project and was pleasantly surprised how easy it was to add those routes.

As Ryan (@modemlooper not McCue) said: API all the things!