The BBC looks at Twitter Bots:
On Twitter, bots are accounts that are run remotely by someone who automates the messages they send and activities they carry out. Some people pay to get bots to follow their account or to dilute chatter about controversial subjects.
“It is difficult to assess exactly how many Twitter users are bots,” said graduate student Juan Echeverria, a computer scientist at UCL, who uncovered the massive networks.
Mr Echeverria’s research began by combing through a sample of 1% of Twitter users in order to get a better understanding of how people use the social network.
However, analysis of the data revealed some strange results that, when probed further, seemed to reveal lots of linked accounts, suggesting one person or group is running the botnet. These accounts did not act like the bots other researchers had found but were clearly not being run by humans.
Via Schneir on Security.