While very basic introductory examples are invaluable in explaining a new API, they can fail to do a rich API justice - especially from the perspective of more experienced developers. For some of us, looking at a slightly more involved, realistic example can shed far better light on the practical value proposition for a technology. A very well written recent blog post on the AMIS technology blog does exactly that for the JBatch API standardized in Java EE 7. The author uses JBatch features such as the Job Specification XML, chunked processing, parameter passing, batchlets, job/step listeners, the job context and integration with Java EE in a non-trivial fashion to create an online download manager. I would say if you are interested in JBatch, the blog entry is almost a must read and perhaps one of the best ones written on JBatch so far.
At JavaOne 2013 IBM Distinguished Engineer Brian Martin presented a very useful session on JBatch titled "Three Key Concepts for Understanding JSR 352: Batch Applications for the Java Platform". Stay tuned to Parleys.com for video of the session to be published. The well-written official specification is also a great place to learn more about JBatch.