Here are some photos of the event so far: http://en.wikipedia.org/wiki/User:Victorgrigas#Berlin_Hackathon_2012 Hopefully I haven't photographed anyone who does not wish to be photographed! Please let me know if I have!
This post was posted by VGrigas (WMF), but signed as Vgrigas.
I uploaded some photos I took to Commons on commons:Category:Hackathon_Berlin_2012. There should not be people with the 'no photo' badge in these.
I also created a category on Commons for pictures taken during the short visit of Berlin (on sunday for my case) commons:Category:Berlin_visit_during_Hackathon_2012