There just isn't enough meaningful things to watch. 3D bluray availability is finally catching up - for the first two years you basically couldn't buy any of them. Avatar was only offered in a $400 box with Panasonic glasses. The Dreamworks Animation films were packed in a $350 Samsung glasses pack.
I'm very surprised Sony/Panasonic/etc haven't teamed up with the networks to do the Superbowl in 3D. If ABC aired another one I'd be inclined to think they would broadcast that way. I know the NBA Finals were.
But the problem inherent with 3D broadcasts is one of bandwidth - 3D is essentially twice the amount of visual data, and there isn't enough room in the pipes to fit it. http://news.cnet.com/8301-17938_105-200 ... broadcast/
With broadcast 3D you're getting less resolution than with 2D. In theory, the Top and Bottom method will look better with sports, as you have more horizontal resolution. But it's actually more complicated than that. As you can see with the numbers above, if you halve 720p in either direction, it's not much higher resolution than DVD. ABC and Fox, and all their related sports programming (including ESPN), made the decision in the early days of HD to go with 720p, as they felt it looked better with fast motion and therefore sports. That means that now they're looking at either having to shoot in 1080i, or supply their viewers with 3D content that's little more than 15 percent better than DVD.
Remember, your cable/satellite box likely defaults to output everything at 1080i, but that doesn't mean that the original source is 1080i.
It's unlikely any cable/satellite provider will increase their bandwidth in the near future to allow for Full HD 3D. So we're left with low resolution images with broadcast 3D.