So yes, we're working on SmarterMail 17 at the moment with a focus on the new features we're going to roll out like MAPI and our own video/web conferencing solution. Both of these require quite a bit of attention, but they'll certainly be worth the effort.
Therefore, we've had to sacrifice a bit of development and documentation time on the new APIs. That said, this is really a good thing for a couple of reasons:
1. Of course, we need to make sure we have everything fully and completely documented and presentable to the public, and
2. They're still somewhat in flux, especially with the new things that are coming out.
While we've gone through some and released them, we still need to go through what's left with a very fine-toothed comb as there could be changes, which would impact users who have them running in a production environment. We don't want the APIs to be a "moving target", which would force users to rewrite code every time something changes in our API and documentation.
More will "become available" -- i.e., documented and publicly available -- with the release of SmarterMail 17, and then more will come post-release. For the time being, using the older APIs is the best way to go.