They weren't using a radio jammer, but using techniques just like were described in the article. We tried getting our gear setup and couldn't get anything working, even trying to use Internet connection sharing over Wifi between a Macbook and an iPad right next to each other wouldn't work. Until we got a hold of the network engineer for the convention and got him to whitelist our MAC addresses on their own APs. Then all of a sudden all our gear sprang to life. He told us they were looking for rogue APs and were sending frames to their clients to disassociate. If you were an attendee and not an exhibitor you could use the free public WiFi that was available. But we were warned that was far too flaky to use for product demos and would require re-registration every hour.
We also had to use commercial grade APs (like Cisco, Aruba, etc.) that could have the signal strength turned way down so it wouldn't bleed too far out of our booth. The WiFi APs at your local Staples don't usually have this option; they only boost the signals, not lower them.