We have released the 1.17 version of Jersey, the open source, production quality, reference implementation of JAX-RS. The JAX-RS 1.1 specification is available at the JCP web site and also available in non-normative HTML here.
For an overview of JAX-RS features read the Jersey user guide. To get started with Jersey read the getting started section of that guide. To understand more about what Jersey depends on read the dependencies section of that guide. See change log here.