http://assembly.galleria.fi/kuvat/Assembly+Summer+2013/ for some photos from the scene, http://www.assembly.org/summer13/ for the actual event.
I believe I have mentioned the event earlier. Check out the photos if you want to see how 6000 computers in a huge arena look like :)
DreamHack in Sweden is considered the world's largest computer festival (Guinness World Records, ~11000 participants) and back in 2011 for the winter 2011 event they did the event with the fastest internet connection - 120 Gbit/s - in coperation with Telia and cisco. They used to run 20 Gbit/s for the event, nowadays 40 Gbit/s. The record was broken the next year in Norway at The Gathering (about the same size as Assembly). They did 200 Gbit/s in coperation with cisco, Huawei, Level 2 and local ISP (Altibox). The norwegians are also now back to the usual bandwidth :)
Hmmm, perhaps one should mention the Assembly organizers that they should beat our neighbouring countries.. the location for the event is excellent for network bandwidth.