So, this topic pretty much explains it all. I've been playing A LOT of SC2 lately, and winning a significant amount of my 1v1 games due to this. Basically what I do is send a worker early in the game to scout and place a proxy pylon in the other idiots base. I wall off my choke, and get 2 cannons. Early gas, quick DT's. If they kill the proxy pylon I get a warp prism, same effect, and usually it's gg (if you're not in Platinum/Diamond league that is).
I'll post a replay when I get home.