I've used PHP for Comet a couple of times and I've never had a massive problem with it. The only thing I found was that the PHP sessions tended to lock the con

I've used PHP for Comet a couple of times and I've never had a massive problem with it. The only thing I found was that the PHP sessions tended to lock the connection, so if you tried to change page it would never load. session_close() seemed to fix this pretty well. Also, It's worth setting a time out because scripts often keep running in the background if the connection isn't closed properly.