Turns out, Blizzard is reporting on its own activities at Leipzig on its official European page. In addition to the Wrath and Starcraft II demo stations, Blizzard hosted the demise of Illidan Stormrage. Uberguild Nihilum performed a Black Temple raid live at the Blizzard booth in front of 5,000 spectators. Afterwards, Blizzard gave away the keyboards signed by members of Nihilum to the crowd. Blizzard also interviewed the guild. You can read it here.
With the convention wrapping up today, we'll have to start looking elsewhere for more news on the upcoming expansion.