Find My iPhone was released in iOS 3, known back then as Firmware 3.0, and you needed a MobileMe account to use it. Now there is nothing wrong with MobileMe(to my knowledge) but I just didn't really need it. So many great apps out on the App Store that can do the same as MobileMe... even better in Cydia.
Now that you got your rant and history lesson, Find My iPhone is now free for everyone who owns an iPhone 4+, iPod Touch 4+, or iPad 1G+ running iOS 4.2 and above. You can now track where you devices are, whether you want to sneak your extra iPod Touch in your wifes purse to see if shes really taking the kids to soccer, or just to find your lost device. It is all free now and it should have been like that in the first place. Apple charging your for MobileMe to find a device you bought from them and cherish.... customer care? Blah.