There is a secret, actually, and for a company that prides itself on making things simple, it's surprising that "Find my iPhone" (which should probably now be renamed "Find my iDevice", but that's another story) is so difficult to set up. The core problem is that while it's been presented as an update to the operating system on the different iOS devices -- notably the iPhone, iPad and latest generation iPod Touch -- it's actually a separate application you need to download to enable and use the service itself.

You'll also need an account on Mobile Me: if you already have a subscription like I do, something I think is well worth the cost, then you're good to go once you log in. If not, you can now sign up for a Find My iPhone-only subset of the service that will have it track your enrolled devices.

Let's start at the beginning, however, because, well, that's a good place to start.

Launch iTunes and go to the App Store. If you're lucky, you might see the Find My iPhone app advertised as a popular app or store selection:

If not, you can just click thru to Find My iPhone [iTunes link], the app:

That's a lot of information to digest, but the key sentence in the description is: "If you lose your iPhone, iPad or iPod touch while on the go, simply install Find My iPhone app on any other iOS device to find it (you must have Find My iPhone set up on the device you are trying to locate)".

So let's do just that!

Tap on 'Free' just under the cool app icon, then 'Download' and you'll be prompted for your iTunes account password, most likely:

You can use mine if you want: abc123. Just kidding, use your own and you'll have better results, I'm sure!

The app downloads fairly quickly on your devices...

And when you launch it, you'll either need to log in to your existing Mobile Me account or follow the Setup Instructions link to learn how to sign up for a Find My iPhone-only Mobile Me account.

Once you do sign in, though, it'll show you where your devices are located on a map. In this instance, I'm looking for my iPhone (ingeniously called "iDave 4") with the Find My iPhone app on my iPad:

There ya go. Neat, simple and any device can now locate the last known position of any other device as long as you have the app installed on all of them.