It looks like Army MARS is leading the pack on this. I hardly ever hear anything about Air Force or Navy MARS activities. I guess my clearance is not high enough.
I don't know much about what AFMARS is doing (I've never been a member), but Navy/Marine Corps MARS has an excellent website, navymars.org. All of their MARS chief's broadcasts to the membership are on the site and open to all. I'm not a MARS member any longer (was Army MARS for quite a while), but I have spoken to the Navy MARS Chief (Bo Lindfors) on several occasions and found him to be very sharp.