The EdgeWalk opened on Aug 1 of this year. Hands down a MUST-DO (is that even a word?) Amazing view, and there is nothing quite like the thrill of adrenaline from looking down at the tiny tiny people below.
We started off in a glass room where they first gave us a breathalyzer and swabbed us for explosive residue, no joke. Then we put on the suits and harnesses and went up a special elevator to the platform. The guide strapped us in and then took us outside, pointed out some landmarks, and walked us through a series of exercises -- walk to the edge, lean backwards, lean forwards.
You get a certificate at the end with 2 pics and a CD. Pics and vid are included in the tour, as are all the other attractions of the CN Tower (skypod, Himalamazon motion ride). Also, the tickets are valid for entry for 3 days.
Definitely worth it in my opinion. But be sure you're set on doing it, as there are no refunds.