As you might know, @comex has released a userland jailbreak that exploits a bug in the iPhone PDF rendering code. He uses it to root your phone and then install Cydia, the alternative app store. Well, it turns out that the Apple WiFi networks in stores automatically redirect you to apple.com when you try and visit this site! Fortunately, all the phones in stores have AT&T plans, so you just have to disable the WiFi and hop on the 3G, which unlike the in-store WiFi, isn't controlled by Apple. And just like that, you can Jailbreak phones while the Apple employees watch helplessly.
Not really, they probably would kick you out of the store if they saw you doing it, but how much can they really blame you, the customer, for visiting a website. If anything, its Apple's fault for making a browser flaw that can be exploited in this way. I'll bet if I bricked my phone using this method, I could get Apple to take back the phone and refund me since its a faulty product with a security flaw. Visiting a specific website can't really void my warranty, can it?