In most of the examples that I have seen so far, JBoss OSGi WABs do not seem to be able to be deloyed if annotated with @WebServlet. In fact, when deployed as a bundle it requires the web.xml to be present and even when the web.xml is present and the servlet is annotated, the wab is never properly deployed (can't reach it through the URL).
Also, can I use CDI, JAX-RS and EJB3 annotations within a JBoss OSGi WAB?
WAB support is currently provided by Pax-Web. We are however moving towards a JBossWeb based implementation. By that time (at the latest) servlet 3.x support should become available.
If interested monitor https://issues.jboss.org/browse/JBOSGI-491