Woohoow, looking very much forward to getting my hands dirty with this one 
JSR 286, WSRP 2.0, REST services, live text, AJAX proxy, … , lots of new sweetness. Oh and did I mention the new page loading model is *fast* (no more full page reloads because of portlets!)
Check out the top 10 new features at IBM
And of course there’s the updated Portal Info Center