On March 29, 2011, a demonstration of a small E-Cat device was given, with Andrea Rossi, Guiseppe Levi, Sergio Focardi, Sven Kullander and Hanno Essen present, and conducted by Rossi and presumably others. According to calculations written up by Essen, 25kWh of excess heat were produced by the device over a period of 6 hours. Given the amount of hydrogen (0.11 g) and nickel (50 g) that were present at the start of the trial, Essen rules out a chemical reaction of some kind.
The demonstration was reported by NyTeknik on April 6. According to the article, Guiseppe Levi is being paid by Rossi to carry out research on the E-Cat at the University of Bologna. Sven Kullander is professor emeritus of physics at Uppsala University and chairman of the energy committee of the Royal Swedish Academy of Sciences. Hanno Essen is an associate professor of physics at the Swedish Royal Institute of Technology and one-time chairman of the Swedish Skeptics Society. I remember reading somewhere that Kullander was on a fact-finding mission, but I don't recall the context.
An English transcript of a radio interview with Sergio Focardi provides additional historical information on the development of the E-Cat. Focardi has not been not privy to the undisclosed "catalyst" that is being added by Rossi to the system in order to facilitate the reaction, though he speculates that it has something to do with preventing the hydrogen ions from forming molecular hydrogen. The interview confirms that gamma radiation is being generated, and for this reason there is lead shielding around the device. Focardi suggests an interesting explanation for what is going on with the gamma rays: a proton is somehow being added to the nickel nucleus by way of an unknown pathway. This results in its transmutation into copper in a highly excited state and the eventual emission of a gamma ray photon. When the gamma ray leaves, the new copper atom recoils like a cannon in the opposite direction. If things were indeed happening like this, the account would go a long way to explain the heat that is generated.