Alard already has some solid info about the system (wow, it's been almost a year since then!) here:
http://tinyrc.com/forums/showthread....threadid=16210
The package I received (so far, I'll be getting more as stuff comes back in stock) is the Sound Tower with 2 Sound Cards, the M4 Sherman with rotating turret and the T34-85 with rotating turret.
Now that I have the Sound System, I have to agree with the comments about adding a whole new level of realism!
The sound is in perfect sync with the Tank movements, very slick. 1 disappointment though, there's no sound for when a Tank is hit (at least not in the 1vs1 no life-limit mode that I've tried so far).
That's it for the moment, pics and vids to come.