JSR 168 vs JSR 286

Features	JSR 168 Specification	JSR 286 Specification
Inter Portlet Communication	Only supported within the same portlet application using session attributes Target portlets will only "see" messages during next render request.	Add additional coordination capabilities Limited only to String Values. Sharing of session data beyond the current Portlet application. Sharing of render parameters across portlets.
Life cycle	Portlets cannot update their state during a render request: "event" handling not really possible	New 3rd life cycle phase before rendering
Portlet Filters	Doesn't Support	Supports Allow on the fly transformations of information in both the request to and the response from the portlet Defined in portlet.xml
Caching		Extended Cache support. Allow public cached content for multiple users
Common Web Frameworks	Servlet dispatching not supported from process Action. Needs Portals Bridges or similar solutions. JSTL support very limited	Extended Cache support. Allow public cached content for multiple users. Improved support for web frameworks (Struts, JSF, Spring) Allow servlet dispatching during all lifecycle calls: processAction, processEvent, render, serverResource. Extended JSP tag library <defineObjects/>, support for JSF
Non HTML Resources(pdf, doc, images etc.)	A portlet can only render html fragments. Have to fallback/delegate to the servlet container. Requires coordination between portlet and servlet.