Q: Apple’s FAQ on creating an iCloud account says if you wish to convert a free “Find My iPhone” account, you should first update your devices to iOS 5. However, one of my devices is an iPhone 3G, which does not run iOS5. If I convert my Find My iPhone account, will it no longer work with Find My iPhone on my iPhone 3G?
A: iCloud accounts can continue to be used with the Find My iPhone feature on older devices. If the account is already configured on your iPhone 3G it should just keep working, and if you ever need to configure it again on that or another older device, simply choose a “MobileMe” account type as you did before and enter your iCloud Apple ID and password.
Note that Find My iPhone is the exception here—the only “MobileMe” account feature that will continue working with an iCloud account. Other MobileMe settings such as Mail, Contacts and Calendars are not compatible with the iCloud versions of those services, which is likely the reason why Apple indicates that you should update your device to iOS 5 before migrating your account.