An interesting tidbit from the official iOS 4.2 press release:
The Find My iPhone (or iPad or iPod touch) feature is now free to use without a MobileMe℠ subscription and helps you locate your missing device.* The Find My iPhone app is a free download on the App Store℠ and lets users easily locate a missing device on a map and have it display a message or play a sound. Users can even remotely lock or wipe data from a lost device to protect privacy.
Apple is making the Find My iPhone feature free for all users running iOS 4.2 on latest generation devices: iPhone 4, iPad or new iPod touch -- as you can see here.
The Find My iPhone feature allows you to remotely locate an iOS device you've previously configured the service on, and also lets you remotely wipe it, or send a message to whomever might have found it. It used to be available to MobileMe subscribers, now Apple is making it free enabling you to activate it using your Apple ID.
The first step towards MobileMe going free, or at least some parts of it? Great move, Apple.