It is under active development (by Me and Malte and his crew). We have it running in production here - which admittedly is a bit bleeding edge and I wouldn't recommend doing so unless you really understand both contacts and ams so you can fix annomolys and bugs as the pop up within a few minutes. We've actually had it in production for about 6 months now... To play with it, or for personal us, HEAD installs nicely on a standard 5.2.2 site with package dependencies taken care of by HEAD. Since i'm in production, and i'm pretty sure one of Malte's clients is as well, we do ensure that the sql and tcl upgrade scripts work (since we need them ourselves)... so if you aren't going into production with a bunch of staff, or for a client, you could try it out.
Once Malte and I finish our current projects I think I'll try to get an official release out, but its my impression that neither of us feel an urgent need to do so since its working for our clients.