This is the rule directly from the Racing Rules of Sailing - 2005-2008:

"40.2 A trapeze or hiking harness shall have a device that can quickly
release the competitor from the boat at any time while in use.
Note: This rule takes effect on 1 January 2006."

At this point, I have yet to see any trapeze system marketed that has such a system. The ball / socket systems are not "quick release."

Looks like everybody's going to be buying something in the next year - we just don't know what yet.