As far as the movies go there really haven't been any notable Superman reboots. Superman Returns was supposed to be in the same continuity as the previous movies. So this would really be the first reboot out there.

I suppose if you throw in all the Superman TV shows though....there are quite a couple, and plenty of people would argue that while Superman Returns was in the same continuity, that because of the long time between Superman movies that it was something of a reboot in itself.

I'm actually a little bummed that they weren't able to keep on with the movies. I liked Superman Returns. It wasn't the best movie ever, but it was pretty decent, and I thought it set the series up nicely for some quality follow ups. I especially liked Brandon Routh as Superman.