I accidentally hit "update all" while on cellular data. When they removed the need to enter your password in iOS 6 I decided to be very careful with this, since I could foresee accidentally using up my data allotment. Not careful enough, I suppose. I tried rebooting the phone and logging out of my App Store account. No luck. The downloads continued. While the apps over 50 mb didn't go through there was enough under to threaten my remaining data limit. I ended up shutting off data completely until I could get a wifi connection. Personally, I would rather enter my pw as a safeguard.