Indeed, my thinking is more to do with personal info. Part of the beauty of these devices is connecting them to your contacts, mail, apps, bookmarks, photos stream etc etc. Now ... I have no secrets from my partner, but equally there is data you want to keep separate. iMessages and emails for example, what a mess to have to sign out of iMessage or jump in and out of each others mailboxes. You still want the personal experience from it and basically turning off iCloud is a waste of the devices integration.
Our iPad sits on the sofa and we both use it to play games, browse the net, but then for example things like FaceTime becomes a pain in the ass because you have to custom add people and not link it back to iCloud lest it merge both your contacts. I've ended up disabling iCloud and dumping half of the iPads built in apps into an unused folder.
I have other similar frustrations and I know there are work arounds for most of those concerns, but a simple log-in system would retain the 'personal' aspect of the device whilst letting it be used by multiple parties. I don't know ... Maybe I'm just trying to use it in the wrong way, but for a living room device it certainly likes to have only one master.
As for sharing among family households, I get the feelng that Apple are seeing a fair number of people who are using it to replace the knackered old laptop or rubbish netbook sitting in the arm of the couch. That doesnt discount that many of us here may be fortunate enough to buy one just for ourselves, but I think a family computer is the reality of how many people are using them.
That became a bit of a rant, a apologise. I love this iPad to bits, I just wish it could outperform my expectations sometimes
