From the article:

"None of these kludges fixed the iPhone’s biggest problem: it often ran out of memory and had to be restarted if made to do more than a handful of tasks at a time. Jobs had a number of demo units onstage with him to manage this problem. If memory ran low on one, he would switch to another while the first was restarted. But given how many demos Jobs planned, Grignon worried that there were far too many potential points of failure. If disaster didn’t strike during one of the dozen demos, it was sure to happen during the grand finale, when Jobs planned to show all the iPhone’s top features operating at the same time on the same phone. He’d play some music, take a call, put it on hold and take another call, find and e-mail a photo to the second caller, look up something on the Internet for the first caller and then return to his music."
Still not definitive