This might show up in future versions of iOS, but for now if you have a jailbroken iPad, you can have multiple user profiles on your iPad with iUsers.
http://www.engadget.com/2011/07/17/iusers-frees-your-ipad-of-monogamy-enables-multiple-user-profil/
Share an iPad? A new tweak is on its way to that other app store
that should make your life a little easier: user profiles for iOS. The
mod, dubbed iUsers, adds a user login button to the iPad's lock screen.
The tweak segregates application data and preferences between users,
meaning that user A's Angry Birds score won't muddle and mix with User
B's perfect three-star rating. App installations, music, and video
content are currently shared between users, but the tweak's creators
hope to remedy that in a future update. It's a jailbreak only mod, of
course, but still a neat feature we'd love to see implemented in future
versions of iOS. The
iUsers tweak should be hitting Cydia soon, but folks who want an early
peek can snag it now by following the instructions in the source link.