The simple answer is yes, cheating is cheating. But if his claims are true that everyone does it and it's the only way to compete, it becomes an issue of enforcing existing rules. Enforcement has to be consistent.
I do think FINA should change their rules w/r/t underwater camera footage in the future, and maybe this Olympics will be a catalyst for that. But unless they can review the other swimmers too to make sure they didn't also break the rule (some of them probably did), I don't think him alone giving up his medal is the solution.
...which is not intended to be an endorsement of what he did (and said after the fact), just an acknowledgement that a forward-looking rule change is the better way to address a problem that all swimmers are dealing with in these events. One of the semifinalists in the 200 IM got DQ'ed for a dolphin kick off the wall on the breaststroke pull out, pretty much the same thing. He was the guy with the 9th fastest time in semi's, so he wasn't going to advance anyway, but obviously this is an issue. He just happened to get caught by an official on the surface, probably because he was in an outside lane and therefore easier to see than van der Burgh was in the middle of the pool in the 100 breast.
I don't think he should give up his medal. Who knows if he's lying or not, but there's always the possibility that other people do this as well. In that case, he was just acting in accordance with the competition, despite the fact that the rules state it is cheating.
The committees need to do a better job of reviewing this kind of thing and should be installing more under water cameras to ensure that athletes don't feel as though they can get away with it.
I'm curious how the second and third place finishers feel in the wake of this and whether or not they pulled the same move as him.
No. Pretty much what Susie said. I think the current system just does not work...and one guy giving up a medal for something that lots of swimmers are apparently doing is not the answer. Also, I agree that it could give unfair advantage to swimmers in the middle lanes who can't be seen (caught) as easily.
1) Why did he admit to it publicly? That's kind of stupid. 2) Although he obviously broke the rules, apparently it's something that's widespread in the sport. If that's in the official rules then they should find a way to enforce it across the board.
it sounds like he admitted it because he wants the underwater cameras at all major events. So while he has everyone's attention (as the gold medalist) he figured why not highlight this major problem that they all know exists but aren't talking about.