camunda BPM comes with a fresh REST API based on JAX-RS. Its goal is to expose the process engine services as broadly as possible. That means we aim to enable you to interact with process engine services via REST with similar expressiveness as in plain Java. With 7.0.0-alpha1, we provide methods such as task querying that already realize our desired degree of detail (similar for process definitions and instances). For future releases, we plan to broaden the scope to reach the afore-mentioned goal.
Independent BPM Analyst Sandy Kemsley writes about the camunda BPM launch on column2: http://www.column2.com/2013/03/stick-a-open-source-fork-in-it-camunda-bpm-splits-from-activiti/
I am proud to announce that today camunda launches a new open source BPM project: camunda BPM. At this juncture we part ways with the Activiti project which we have contributed to since the first days. Leaving Activiti is a sad but necessary step for us. Starting as a consulting company, we have built a customer base of 250+ in little over 4 years. Last year, we entered the BPM vendor business with the camunda fox BPM platform.