Based on a scientific analysis of more than 2.6 million tweets, UK newspaper The Guardian presents "Riot Rumours" [guardian.co.uk]. The online visualization aims to explore how various false rumors in regards to the riots came to be: for instance, at some point in time, it was believed the London Eye was set on fire, the army was deployed, and that some rioters took over a local McDonalds to cook some food.
Each bubble represents a unique tweet, of which the surface area corresponds to the influence of its author, i.e. the amount of followers he or she has. The color of a bubble has a qualitative value, that is whether the content of the tweet was in 'support' or in 'opposition' of the specific rumor, or was just a neutral comment. The color brightness corresponds to the relative time since the tweet was posted. An interactive timeline allows for animating the bubble graph to investigate how various rumors were started, supported, and then denied via the Twitter medium.
Interestingly, Bryan Connor over at the The Why Axis, already posted an interesting design review of this very visualization.
See also "Twitter Traffic during the Riots", also by The Guardian Interactive.