[Al Skierkiewicz]

Dave,
As a strict intrepretation of the rules from 2003 and those relating to custom circuit boards, custom circuits may not directly connect to any motors. They may connect to sensors on the robot and to the robot controller. As an alternative, you could use one of the provided servoes to actuate a brake band in a custom transmission and I think that would fit in the rules under both mechanical and electrical rules. If you were to design a transmission that needed to use a motor in freewheel at one time and brake at another time you could use a servo to actuate a microswitch that in turn connected to the brake jumper on the speed controller. This is an alternative that has been used by teams for many years. The servo, under software, moves to close or open the microswitch thus switching the speed controller from brake to coast.
I doubt that the staff will make much of a change in this area of the rulebook over last year. It is a safety issue more than anything else.
I hope Paul sees this post and comments but my understanding of the Thunderchicken tranny was that the second motor added more power to the system not simply to change speed. Look close and I think you will see that the ring gear can be either driven one direction or the other or stopped. I will defer to Paul who is way better at describing this.