We use jetty to handle about 6 million page views a month, and it has no problems with the load, or stability. I do have two problems with it though. I'd like a cleaner way to handle SOAP. currently I have to include Axis or something, It would be nice if I could just use the new @WebService annotations and roll. This probably isn't a real problem, just haven't really finished my research on the subject yet, but it would be nice if this were included. Wouldn't mind an article on this either..</hint>
The other thing that I don't really care for is the need to restart the service when the war file is changed. This can all be done by hand of course, but it would be a nice simple thing to include.
On the good side though, Jetty is small, simple to configure and administrate, and much more pleasent to work with than anything else I've used. Give it a try, we've been using it for 3+ years I think. I got addicted to it when it was part of JBoss.