Jobs said from stage, and an Apple engineer later told InfoWorld, that over 500 WiFi networks were in operation. Not 500 WiFi adapters or connections—in an audience of 5,000, there could have been thousands—but 500 distinct networks.
Most of these networks were apparently generated by people using a MiFi, a cellular gateway from Novatel Wireless, sold by Verizon Wireless and Sprint Nextel, which relays 3G networks over WiFi.
However, after examining the video from the event and discussing it with two veteran WiFi gurus, it seems almost certain that the MiFi was only part of the problem. A flaw in the pre-release iPhone 4 iOS was clearly another element. Apple’s public relations confirmed receipt of a request for comment, but none was forthcoming.
Fleishman puts forth a pretty good argument — the whole thing is a good read.