Ydna made the first one I was aware of, but I'm not even sure he was the first.
ZDS Paintball - My Markers - Mechanical Ion
Since one eventually always brings up patents when discussing the Gardners, it would be interesting to see if Colin Bryant Moritz has anything to say about this new marker:
Patent US6990971 - Pneumatically amplified trigger actuator for a gas operated marker gun - Google Patents
Not directly applicable, but it's the first patent that came to my mind vaguely similar to this marker.