Do you think iPad is a personal device? Well I think it's a very personal device, though we don't carry it along all the times like iPhone or iPod Touch. We often come across situations where we need to share it with our family members or friends. There is nothing wrong in sharing it, except that one needs to logout from all the applications and stuff containing personal information like emails, facebook, twitter etc.
iPad really lacks a true multi-user support, this is something Apple should look into and bring in iOS 5. BERG Studios has suggested a nice multi-user UI concept for iPad. It's shown as a built-in feature which can support up to four users. The design shows an unlock bar for each user at four corners of iPad lockscreen. The concept also shows the pass code support for individual accounts and a notification indicator present next to user accounts to show new updates.
This is really what many iPad users demand, hopefully we'd see some multi-user support in future iOS versions for iPad.