The main research focus of the HP Information Dynamics Laboratory is on the relation between the local actions and the global behavior of large distributed systems. They explore distributed knowledge, social organizations, and novel economic mechanisms, among other research areas.
On the seminal paper Implicit Structure and the Dynamics of Blogspace, the authors explore information epidemics in the context of blogspace. As they explain: "Weblogs link together in a complex structure through which new ideas and discourse can flow. Such a structure is ideal for the study of the propagation of information". The authors described general categories of information epidemics and created a tool to infer and visualize the paths specific infections take through the network. They concluded with a description of a new ranking algorithm, iRank, for blogs. In contrast to traditional ranking strategies, iRank acts on the implicit link structure to find those blogs that initiate these epidemics.
Although a bit poor in their visualization techniques, this paper is extremely relevant in the understanding of Information Diffusion among social networks, an area that has been intriguing sociologists, and lately marketeers, for quite some time. Their major breakthrough was announcing that the most popular blogs are not the most innovative, by commonly "stealing" news and information from smaller, less-known blog sources. This is a very significant allegation that decisively influences the way we understand the mechanics of blog communities.
You can read the paper here.