Zuckerberg being a terrible speaker (2010): http://www.youtube.com/watch?v=o3hu3iG8B2g

Zuckerberg being a brilliant speaker (2011): http://www.youtube.com/watch?v=1OQQ4E2k0Mk

Notice how he seems to be more confident and relaxed when he speaks. Unlike in the AllThingsD interview, this time he uses pauses and gestures effectively as well.