This question was addressed in
this thread in the official
FIRST Q&A System. Gravity-based deployment of ramps is permitted, as long as it is done in a safe manner and does not cause damage to the field. If you are using this type of system, print out a copy of the official Q&A answer and take it with you to the competition, just in case there is a question about it during inspection.
-dave
remember - the
FIRST Q&A System is the only resource for official answers regarding the 2007 FRC competition. The Q&A is your friend. Use it. Learn it. Know it.