I haven't used Ruby On Rails, but here's an interesting comment that might give Cayenne some future direction goals. Of course, I'm not entirely certain what he's talking about :)
Java Web Framework Sweet Spots - by Matt Raible JavaWebFrameworkSweetSpots.pdf http://www.virtuas.com/files/JavaWebFrameworkSweetSpots.pdf WebWork 6. What do you think of Ruby on Rails? • The integrated stack is amazing. They did a great job here, and there is room for Java to offer something similar. WebWork could easily be the web stack, but the persistence solutions aren't very promising right now. The biggest issue is that while WebWork and SiteMesh, for example, support configuration reloading and even dynamic class reloading, Spring, iBatis, and Hibernate do not. They need to step up to the plate and at a minimum support configuration reloading before a good stack similar to Rails can be offered. Similarly, Hibernate and iBatis offer poor hooks into the guts of their framework like WebWork does. With a single class, I was able to get rid of the requirement for xwork.xml in WebWork. That cannot be said for the persistence libraries. Once they get their act together, perhaps a complete stack can be pushed out that does all the things Rails does.
