Apple restricts the free find my iDevice apps to iPhone 4, iPad, or iPod touch (4th generation. However with a few easy steps you can set find my iPhone on any GPS enabled iDevice. All you need is someone with one of the devices that are supported by the app, and an email address to link a mobile me account to.
Find a friend (or a really nice stranger) who has an iPhone 4, iPad, or fourth generation iTouch.
On their device go to settings/mail, contacts, calendars/add account. Press create a free Apple ID. Create the account and verify it in your email account that you create it with.
Log into find my iphone on the device that you are borrowing. Make sure it is working properly.
Go back to your iDevice. Download find my iPhone, iPad, or iPod Touch. Log in with the Apple ID that you created on the borrowed device. It should now be working on your device.
Go to me.com and see where you iPhone is. Test the features, try the display message feature. If these are all working then you can now rest easy knowing you will always know where you device is, and that your data is safe.