Hossam, who has a history of activism in left-wing groups and at the American University in Cairo, has been arrested before. One time was in front of my very eyes as we were coming out of the Hardees on Midan Tahrir in Spring 2003. He was not doing anything and was not involved in the protests taking place that day, but a State Security officer had decided to arrest him nonetheless.
Hopefully there will be more information about this later on from people on the scene. Let's hope those who were arrested today don't get the same brutal treatment others recently received.
Update: Just heard from Hossam, he said he was "attacked by five plainclothes thugs who smashed his camera and detained him for 15mins." The others are still under arrest.