Polling works out of the box with pretty much all web servers - the downside is that it's significantly slower and more resource intensive than comet.

>> the downside is that it's significantly slower and more resource intensive than comet.

Any data or story to back that argument? Just curious.

I don't have data available right now, but I have done quite a bit of research on server push technologies for one of my projects. It just comes down to bandwidth: regular polling consumes bandwidth (and the related client and server resources) even when there's no actual data being sent.