Ios 5

With the release of IOS 5 and the new Notification centre coming to IOS devices, it looks good, but i have a query regarding this.

After looking at WWDC keynote from IOS, the Notification Centre can be accessed directly from the Lock screen, while this may be good. I'm wondering how this would impact security ? As you respond to notification(s) , or apps alerting the user to the notification, what happens afterwards? And more importantly, what happens period? Is just the app unlocked, and only that app, and after the user does what they need the phone re-locks itself? or once you accept to a notification from the Lock screen, the phone unlocks. ?

This would be good if it was your intention, but what if your IPhone, IPad etc was in the hands of someone else. stolen etc.. ?