The auto-generation of WADL documents has been supported in CXF JAX-RS for a while. Letting users get a WADL instance and use a tool like soapUI to test a live RESTful endpoint is very useful.
Don't get distracted by the fact WADL is not favoured by some REST advocates. Being able to test a live endpoint without spending time on writing a dedicated test code is good.
CXF JAX-RS also offers a CodeGenerator filter which can be configured on test/development/POC servers for possible users being able to download the source code, compile it and start experimenting immediately. Java is just the only option there for now but of course more languages can be supported easily.
That is all fine, but one limitation there is that what is possibly the most important WADL feature, underrated at the moment, is not really utilized. WADL is very resource centric and IMHO it's a perfect language for bridging would-be RESTful application modeling tools with the actual code. I'm not referring to UML-like modeling but a more high level approach with a tool linking entities representing root resources, subresources and data and using WADL as a internal link between a specific tool data representation and a wadl2java code generator. I'm not referring to a complex WADL XML editor here.
All/most of us do Java-first development and it's kind of easy to assume that nobody will need a document-first development. But the document-first approach has its followers as it has its benefits.
CXF is all about choice, options, diversity and letting users get their web services projects done using the strategies preferred in their teams. CXF 2.4.1 offers a server side WADL-first development support - give it a try and enjoy.