Me too thought the same but got confused with few things. To be more specific... in my application while retriving the session id i noticed that I can get id in two ways. One was to use "request.getRequestedSessionId()" and the other being "request.getPortletSession().getId()" and both being two unique ids everytime so dont know exactly what they are. Could you please explain or guide me.
I think you're confusing the Http Session with PortletSession. PortletSession is part of the infrastructure that keeps different portlets in a portlet container from losing their internal state as you pop between different portlets and Java's HTTP scope doesn't really apply for that sot of world-view. But for a more intelligent explanation, ask in the Portlet forum.
An IDE is no substitute for an Intelligent Developer.