AFAIK, Seam 3 has Web Beans as the core. So it's Web Beans plus extensions like the iText, PDF, email, Excel, Seam remoting, Seam custom tags, etc. There is a SPI in Web Beans that allows the following:
Web Beans is intended to be a platform for frameworks, extensions and integration with other technologies. Therefore, Web Beans exposes a set of SPIs for the use of developers of portable extensions to Web Beans. For example, the following kinds of extensions were envisaged by the designers of Web Beans: • integration with Business Process Management engines, • integration with third-party frameworks such as Spring, Seam, GWT or Wicket, and • new technology based upon the Web Beans programming model.
If you are considering writing an external-facing app with high userbase/load, you're probably better off waiting for Seam 3 as there are considerable performance optimizations with JSF 2.0 and dependency injection, interceptors, etc. How significant these improvements will be is unknown (in prod envmts) at this time.
I am not sure what the plan is for migration of Seam 2 to Seam 3 apps, although I believe Seam 3 is supposed to be backwards-compatible.
Also, since Web Beans uses @PersistenceContext to inject an EntityManager interface instance, I'm not sure if the SMPC will be supported as well as Hibernate MANUAL flush. I imagine it will be to support atomic conversations as this is one of the
pinnaclesof the Seam framework (something that has solved a lot of problems including the dreaded Hibernate LazyInitializationException with Spring).
Here is a useful link on porting status: http://seamframework.org/Documentation/Seam3PortingStatus
Also, from JBoss's track record in terms of JIRA issues/bugs, etc. even with their GA releases, you should continue with Seam 2 for now.
Web Beans and EE 6 are not completely final yet AFAIK and currently there is only one implementation of EE 6 (Glassfish V3, the reference implementation).
By the time Seam 3 is stable, it will be 6-12 months easy.
Stick with Seam 2 for development/prod deployment for now...
Thanks a lot for the input and some clarifications... You're right about backwards compatibility, Seam 2 and 3 will be 100% interoperable, or at least that's what I keep hearing. I've just read Gavin's
Introduction to WebBeansand it seems to be just as I feared - it renders the current knowledge of Seam pretty useless.
I almost can't believe how bad time I chose to discover this wonderful framework that Seam is.