I know these three couples. All six people have iPhones, and they have all recently asked me about syncing. I told them to wait until iCloud came out so I could give them a more informed answer.
I know that once you have iOS 5 on your phones, you can have separate iCloud accounts while sharing an iTunes Store account between you. That is not my question.
But to get iOS 5 on your phone, you have to plug it in and sync it with iTunes one last time. I can't test this, but I'm assuming that unless you create separate Windows or OS X accounts for that one lousy sync, you can't do it without screwing up at least one person's data.
That is my question: Is there a good way to install iOS 5 on two iPhones, from one computer account, without causing the data apocalypse you're trying to avoid by upgrading to iOS 5 in the first place?
EDIT: It occurs to me that after I plug in the phone, I could just uncheck every single "Sync" option underneath the tabs on the device screen in iTunes. Is that all it would take to upgrade to iOS 5 but leave the device untouched?