it's not nearly done. We had some initial setup done roughly a year ago. Lately Joseph is tackling it more fully, so currently the project is quite active (and Joseph carries the vast majority of it). But on many things we're still in the design phase. So you're welcome to participate in discussion on that repository. The overall aim is to have a tagging-aware and compatible replacement of `beamer` that has sane and idiomatic LaTeX under the hood (don't understand me wrong, `beamer` is an amazing thing, but it consists of many incoherent, undocumented, and very non-standard parts of code).