Lift's demo site and Buy a Feature and a bunch of smaller Lift-based
projects all go through Apache.
Apache is good for about 300-400 simultaneous connections. Tomcat is
also good for only 300-400 simultaneous connections. So for small to
moderate Comet site, you'll be fine.
When we ran a huge Buy a Feature tournament, I ran it with Jetty
connected directly to port 80.
I am currently working on (with Tim's help) using NginX as a front-end
proxy to Jetty. NginX can support C10K (10,000 connections). Once I
get some configuration files for NginX put together, I'll send them out.
Thanks,
David