Recently I installed and successfully deployed a ESRI ArcGIS Server based Java Web Mapping application on Jetty 6.1.14
Though Jetty is not officially supported deployment container, since its standards based it works without any issues.
For starters, if you are new to Jetty or if you are looking for an alternative to Tomcat find out more on Jetty at http://www.mortbay.org/jetty/
Steps to deploy web mapping application:
1. Download and install Jetty 6.x version on to the machine.
2. Export war file either from Manager or Eclipse
3. Navigate to <jetty root >\webapps folder and drop the war file
4. Start jetty in command line:
java -jar etc\jetty.xml 1>logs/out.log 2>logs/err.log
or create a batch file and paste the above line in the batch file
5. Access the webapplication at: http://localhost:8080/<web app name>
For folks looking into using Jetty with Eclipse, you will have to install a plugin. Here is a good link showing how to go about it : http://docs.codehaus.org/display/JETTY/Web+Tooling+Support