Scinet is an opportunity for the vendors at the conference to chip-in to the network infrastructure and showoff their goods. They try to use Scinet as a demonstration of the latest technology that they are developing.
So from year to year you're bound to see new stuff. Refer to the pictures that follow to get an idea of what's here. There is a large wall of networking equipment behind plexiglass that is the Network Operations Center of the conference. In addition to that, there are satellite locations that contain a single rack with networking equipment that supports the booths in the area.
In addition to the networking, Scinet runs security related tools on the network. Tools like Bro to detect various intrusion related events. They also have a wall-of-shame being continually updated with passwords that have been collected off the wire due to poor computer security practices. It's an effective way of showing the attendees just what is possible if you're ignorant of proper compsec practices.
Most (all?) of Scinet is fiber (or I didn't see much copper) and since it's the biggest iron that the vendors can provide, I think many of the switches and routers you see in the pics are at least 10 Gig; probably more 40+ though.