I don't think releasing should be an issue for most teams. If you are using pneumatics with a single solenoid, it will most likely (if you wired it right) release when the control system is disabled. If you are using a double solenoid, you can vent the pneumatic's system.
The only other mechanism teams seem to be using is a solenoid, or some type of spring mechanism, which should be easy enough to release when you tug on the right parts
