I just caught up with this awesome tool from the New York Times R&D Lab. (Shouldn't everyone have an R&D Lab?).
It's a homegrown tracker that takes tweets and retweets and allows visualization across a number of parameters. What's especially pleasing about this is the quality of the visualization, which is helpful in understanding how this information moves across time as well as building up an understanding of how certain nodes, (i.e. influential tweeters), affect the spread of information. The video above tracks the data from one of my favorite articles of the past year: "But Will It Make You Happy".
This is the kind of thing that is going to be highly useful to anyone interested in understanding and manipulating the new world of content curation like, ummm...the New York Times.
What is also interesting is that by accessing twitter data the Times is accessing personally identifiable tweets. For example, at 2:01 in the Project Cascade intro video, you can just make out Tim O'Reilly's effect as a colossal node in retweeting a Paul Krugman article. Again this brings up the tradeoff of privacy versus the opportunity to leverage data resources to help us better understand and visualize the world.
I may be naive, but I generally vote for the latter.