Using R, below is the network visualization for the last 100 tweets using the hashtag #SEMXX (used by tweeps at the AACRAO Strategic Enrollment Management Conference)
Below is a key actor analysis based on measures of eigenvector centrality and betweeness derived from the network data from the visualization above.
A great presentation on utilizing metrics from social network analysis can be found here:
I also suggest the following video:
I plan a more formal entry with details related to centrality, be-tweeness etc. at a later date.