Caucho's Resin application server has achieved Java EE 6 Web Profile Compliance. Congratulations to the team on reaching this milestone! Resin is an interesting case because it's actually a new player in the Java EE arena taking the opportunity of the new Java EE 6.0 Web Profile specification to achieve compatibility.
As a reminder, the Web Profile includes Servlet 3.0 (of course), but also JSF 2.0, EJB 3.1 lite, CDI 1.0, Bean Validation 1.0, JPA 2.0, JTA and other supporting technologies. By betting on this rich set of technologies, web developers are free to chose the runtime of their choice, and that now includes Caucho's Resin.
Note that Resin shares with GlassFish and WebLogic the same JPA (EclipseLink) and JSF (Mojarra) implementations while implementing their own JMS broker (an optional technology in addition to the Web Profile) and of course CanDI, their CDI implementation.
Caucho has also posted a roadmap document indicating that Resin 4.0.18 will be a certified "beta release" with 4.1 being the "stable release" soon after. Resin is available in open source (GPLv2) version as well as via a professional and enterprise editions.