I showed a graph of the agu10 archive here, and more recently the agu11/2011 archive here, and now for the agu12/2012 archive. See the 2011 post for the exact methods used to get the data and to clean it.
I will have to review methods to show this, but from appearances, the networks are becoming more like hairballs. In the first year, half the people were connected to theAGU and the other half were connected to NASA, but very few were connected to both. The other prominent nodes were pretty much all institutional accounts. In 2011, that started to decrease and now in 2012 you can't really see that division at all. There are the top three nodes - two the same plus a NASA robotic mission - but then there's a large second group with degrees (connections to others) around 40-80 (combined indegree and outdegree) of individual scientists.