Well, it is only pushed by RedHat (hence the adoption by Fedora only) so progress is slow. But steady I'd say. There are patch for a lots of server and SystemTap seems compatible with Dtrace entrypoints so I guess the thing now is to document it better.

A "state of the Union" document and good documentation and example would indeed be very welcome. It's a very promising and underestimated piece of technology. I'm really enthusiastic about it but I didn't take the time to study it yet.