MacRumors was smart about it. They had JavaScript that would poll for updates once a minute, and a little spinny thing to make the users think it was constantly updating. Far less load than having users refresh the entire page every 5 seconds.

Would have been nice to try comet out in that situation, it seems like a more appropriate technology

Comet is neat, but in broadcast situations like this it doesn't really matter if there's a delay, just like it doesn't matter that there's a 10 second delay for radio listeners.