Using Apple’s MobileMe to locate your iphone or ipad is now free. Has been for some time. If you have an iPhone 4, iPad, or 4th generation iPod touch (iOS 4.2 required), then what are you waiting for?

If you’re afraid of black helicopters appearing over your house, or you KNOW which size of tin foil hat fits you best, then stop reading this post now. You’re too paranoid to own a computer… (well..maybe you’re just too smart to own one).

For the rest of you who simply want to find your iPhone when it disappears or slips behind the couch when you’re knockin’ boots with your significant other, then keep reading.

My first hang up with this was that MobileMe used to cost money. It still does. But if you just want the “Find My iPhone” service turned on, it’s FREE.  Setup is a little wacky, so let’s get started.

1. On your iphone Download the Where Is My iPhone app.

2. Once you have that downloaded and installed, then you’ll be prompted to update your MobileMe account in your email. Do this:

a. Go to Settings on your iPhone (or iPad)

b. Go to Mail, Contacts, Calendars

c. Select Add Account

d. Select MobileMe from the list

e. Enter your Apple iTunes ID and your Password. (you just used your password to download the app, right? Same one here. Now for those of you with iTunes password amnesia–you know who you are–you can’t do any of this w/out your iTunes password. So go reset it and then come back when you’re ready.

f.  Turn ON “Find My iPhone” this screen will automatically appear once Apple has verified your MobileMe credentials.

Obviously if you’ve lost your phone, then you’re not going to be able to use it for finding it. (was it really necessary for me to say that?) So. Now fire up your web browser and go to Apple’s MobileMe page. Do this:

a. Login using your iTunes credentials (the same ones we’ve been using all along)

b. Marvel as the computer map appears showing you where your phone is.

c. Note the options you have when your phone is found: Display a Message or Play a Sound. Sending a remote message is good for harassing whoever has your phone. The sound is annoying enough to be heard anywhere in a room (or from under the couch). You can also remotely LOCK the phone. This is useful when your kids won’t give up on Angry Birds. You can also WIPE the phone’s data. (same goes for the iPad).

If you have an iPad, you can follow the same instructions to add it to your list of trackable devices.

Now, if only I had the same thing for my bluetooth headset. (not to mention the keys to my truck or…alas…my brain.)