I have to agree with Ontario Diver. Technical diving is actually being commintted to understanding why and how long and how the hell you can do it safely. A recreation diver will jump on a vacation boat, throw on some rented gear and hit the water to look around. A technical diver will understand that he (or she) can't just throw on some gear and hit the water. I would have to add that there are speciality areas within technical diving and you all have hit on them, (i.e. cave, wreck, deco obligation, etc.) but the bottom line is you don't have to breath nitrox or trimix to be a technical diver. I consider my daughter (age 16) a technical diver even when she's just running the video camera at 70' on air because she has learned to dive right, learned to DIR as it were, and has the bungeed reg, the long hose primary and an understanding to go with it... and that makes you aware of your actions, the results of your actions (or lack thereof) and what to do when you run across a problem or 'glitch' in your dive, like OOA or other problems. Techincal divers are a more instructed diver group, either from experience or from classes or both. The deeper into the technical field of diving you go, the more you realize the crap can kill you, and the more you understand the need for the right gear and practice, practice, practice with it.
just my opinion but well thought out.
db