Jetty has a CacheControl parameter (can be specified webdefault.xml) that determines the caching behavior of clients (by affecting headers sent to clients).
Does Tom
There actually are several elements in the Tomcat configuration which directly affect this. See documentation at http://tomcat.apache.org/tomcat-6.0-doc/config/valve.html for example.
Atlassian recommends the following two statements to ENABLE browser-side caching so that Microsoft Internet Explorer will be able to correctly download and view attached documents: