It is the 10237 The Tower of Orthanc. This is one of the most iconic structures in the LOTR movies and is the literal centerpiece in the Battle of Isengard.
Also in this battle were the Ents so we are glad to see an Ent in this exciting set.
There are five minifigures in this set:
Gandalf the Grey
Besides the minifigures there are the Ent, a brick built figure, and the eagle, special mold.
The entire set is 2359 pieces and stands 73 centimeters high. Check out more images on the Brickset Photostream.
The designer video was also released this weekend:
The set will be available from Lego Shop@Home from the beginning of July.