Some time ago I read an article what is expected to be in Servlet API 3.0. I remember I read that you can save some .jsp files in a /WEB-INF/lib/somelib.jar/META-INF/web/.jsp and this resources will be exposed to the context root of the web application.
I have just installed Tomcat7 to give it a try, but I found no documentation that I can put some web-resources in jar-files.
There is a feature in servlet 3.0 that allows you to package resources (images, jsp, etc.) in a JAR file. What you do is in your jar file, you create META-INF/resources and dump anything you want in there including directories for structuring your resources. What happens is that META-INF/resources will be mapped to the docroot of your web application.
When there is a clash of resource between your app and the JAR file, your apps resource will be returned. See this
Tomcat 7 supports Servlet 3 so it should support this feature