NBC is supposed to have a lot of stuff on their site, but I haven't looked. Watch their morning show (would that be the Today Show?). I'd be shocked if they didn't replay at least some of it.
Found the video here. What a race! http://www.nbcolympics.com/swimming/?forcereload=true
I did see a replay a while ago this morning.
No doubt it will be shown over and over during the day.
Definitely something to behold.