The NY Times follows some of those wires (and wireless signals) around the DNC's FleetCenter home: This thorough report by Seth Schiesel follows some of the complexity managing wired and frequencies at an event of the scale of the DNC. After reading this article, I'm amazed that anything manages to work. Other stories in this vein indicate that thousands of miles of wire were pulled for this week, while the RNC venue in New York might top 40,000 miles because of some slightly longer distances involved in two spaces being used.
The Wi-Fi problem is clearly explained, and it appears that the planners did hope to reserve space for Wi-Fi. I'm guessing that the wireless equipment used by camera operators is incredibly noisy, spewing out far more than is legal out-of-band (slop-over) signal. Because Wi-Fi has such a low amount of legal signal, it's very likely that the electronic newsgathering (ENG) is treading all over its neighbor's space. There should be at least a few clear Wi-Fi channels.
The network is apparently geared to handle the equivalent of 3,000 T-1 lines--but tell that to my buddy who not only didn't get his paid-for T-1 line drop, but was told there was nothing that Verizon could do about it.