The Find My Friends App requires the minor inconvenience that all your friends have the App installed to, and accept your ‘friend’ request within the App in order to share their location with you.
Find My Friends allows you to easily locate your friends and family from your iPhone, iPad, or iPod touch. Install this free app on your iOS 5 device and sign in with the Apple ID you use with iCloud. Adding a friend is easy – just send a request to see their location. Once your friend accepts using the Find My Friends app, you will then be able to see that friend’s location on a list or on a map.