There is a healthy proliferation of popular frameworks that people are using for their apps on RUN@cloud, here are some pointers for those interested in these:
Grails
CloudBees Grails Plugin - created by Marco Vermeulen leveraging the newly open sourced cloudbees-client-api
Scala
CloudBees Plugin - created by Tim Perrett (blog post )
Play Framework
CloudBees Plugin for play!
Railo CFML (Cold Fusion)