Craig Hockenberry over at his personal blog:
“My iPad has a lot of personal information on it: email, business documents, and financial data. When you pass it around, you’re giving everyone who touches it the opportunity to mess with your private life, whether intentionally or not. That makes me uneasy.
[…]
I can envision several ways to solve this problem: either with a traditional login screen or with something new like folders that require a passcode to open. I have no doubt that your designers can find something elegant that gives me peace of mind as I share my iPad with friends and family.”