I searched and couldn't find this posted, but I could have missed it.
Anyways, its pretty interesting because the official basically says Cavic touched first, but didn't "push" and slid, while Phelps pushed with force, etc etc. (He talks about this right at halfway through the video)
www.swimchampions.com/.../
Personally I think you have to live with however the time system works as long as it is functional. If it was functional and Cavic didn't press hard enough, its tough luck.
The only alternative is to just present a "tie" when you are within the margin of error of the equipment.