The full release notes are available on jira, the artifacts are built and published on Maven repositories and the sources are on GitHub as usual ;-)
To align with the WildFly roadmap and increase adoption, during the last month the team has worked hard on backporting most of the new features and all bug fixes contributed so far on master to a new dev stream forked from the 3.0.x branch. The result is today's release of RESTEasy 3.5.0.Final, which is helping WildFly on the road to Java EE 8 compliance by providing JAX-RS 2.1 implementation while ensuring full backward compatibility with the RESTEasy versions it previously shipped with.
RESTEasy 3.5.0.Final basically allows easy access to the 4.0.0.Beta1 / 4.0.0.Beta2 stable features by offering a painless upgrade path to the 3.0.x users.
The natural upgrade path for users already on RESTEasy 3.1 series is straight to RESTEasy 4.0.0.Beta2 instead.