No, you mustn't, and you probably shouldn't either. Just because my wife and I both want to own Hanging With Friends, that doesn't mean that we want to share the same contacts, inbox, or bookmarks. Using our existing Apple ID for iCloud would lead to just such unintended, undesired sharing. And sharing iCloud accounts would also mean that we have to share our backup space; we get 5GB of free iCloud storage from Apple, but merely updating my iPad and iPhone gobbled up more than 3 of those gigabytes. If my wife wanted to back up her iPad and iPhone to the same iCloud account as me, we'd be up iCloud creek without a parachute--by which I mean, we'd quickly run out of free space.

The good news is that you can continue to share an Apple ID for iTunes purchases with your family while maintaining individual, separate iCloud accounts. And the even better news is that Apple , so you needn't feel guilty about it.

Here's how to set things up:

Either from your Lion Mac or your iOS 5 device, enter iCloud's settings. On the Mac, look in System Preferences; on the iOS device, launch Settings. By default, iCloud on your iOS device may assume you want to use your standard Apple ID--the one you use when purchasing apps--for iCloud, but you're not to do so.

: Were you so eager that you already configured iCloud using your standard, app-buying Apple ID? Fret not. You can click Sign Out on your Mac to get out of that account, though you'll need to click through a few friendly dialog boxes first. (Your Mac will confirm that by signing out you'll lose access to Documents in the Cloud, Contacts, and the like, and ask if you want to keep or remove from this Mac such iCloud-stored data. Don't worry too much; your data is safely in iCloud if all else fails.) On your iPhone or iPad, you can remove your now-unwanted iCloud account from the bottom of the iCloud section of Settings. Tap into your iCloud account there, scroll to the bottom, and tap Delete Account.