My first go around on reading this and I was going to say what BS, thankfully I re-read it in a clearer light. Yeah they had weeks to develop the hack, heck they likely spent months, but that's what hackers do.
The fact is they are only showing you the quickest easiest exploits they know, this doesn't mean that is all they know. In fact these guys get paid "x" times more money than they can actually win at Pwn@Own for showing companies some of the real hard core exploits they now.
The way Pwn@ Own was originally setup the goal was to hack your target machine as quickly and effectively as possible. Now with individual pairings they could've taken their time, but why when they could show the world just how easy it is to do.