The Turbo-Putt is designed like a saw blade, with nubs all around the outside of the rim. It's designed to be used to turbo-putt, which is a putting technique. It's hard to explain, but if I'm stuck behind a something and I can't get a regular putting motion, I'll put my fingers on the outside and top of the rim with my thumb on the bottom of the flight plate, then sort-of fire the disc at the basket like a football. Bad explanation, but you get the gist. Anyway, the nubs on the outside are grooves for your fingers, and there is a swirl on the bottom so you can wedge your thumb into something for better grip. Really, it's sort-of a novelty disc. It was first approved, but there was a bunch of uproar since technically it is not round. There was also some concern that it was unsafe, but hit a guy in the head with a Turbo-Putt and then hit him in the head with a Pro Destroyer and see which gash needs more stitches.
There was some other stuff going on as well (the SL was ruled illegal briefly on a technicality.) So the rules were revised and the Turbo-Putt become illegal after this year. Not a great big deal, really.
They also put a limit on the size of the rim, which was a bigger deal. 2.4 cm., if I recall correctly. So once Innova comes out with their "Speed 14" discs, that will be all she wrote for the "Bigger rim, faster disc" race we have been in for the last 10 years or so. That is why the Monarch all of a sudden showed up. The manufacturers will have to develop new tricks from here on out since the rims are about as big as they can get.
The Turbo-Putt was really the only disc affected. The Epic could have been since at it's widest spot the rim is bigger than the max, but it is grandfathered in and will not loose it's approval. The Wheel was kind-of a gray area, but there were reasons NOT to approve it under the old rules so I don't think it would have been approved one way or the other. The story I heard was that Steve at Quest knew that the PDGA was going to revise the tech standards, so he was hung out to dry...he could not go forward with any new designs not knowing what the new standards were going to be, and the PDGA was dragging its feet and not doing anything. He released the Wheel and Viola!...the tech standards revision email came out the next week. The rumor was that he knew all along that it would not be approved, and he only released it to force the PDGA to do something. In the end he determined the rim size limit by releasing the Double D, as it was slated to be grandfathered in with a smaller rim limit but the other manufacturers argued that it would be unfair for Quest to be the only company with a disc that fast. So the Double D rim size became the legal limit by default.