467 million Twitter posts from 20 million users covering a 7 month period from June 1 2009 to December 31 2009. We estimate this is about 20-30% of all public tweets published on Twitter during the particular time frame.
For each public tweet the following information is available:
We have no Twitter social graph (who-follows-whom graph) available. You can find a copy of the graph here (thanks to Haewoon Kwak, et al.).