Rafael Rivera, Long Zheng and Chris Walsh has released an app named ChevronWP7 which enables you to jailbreak or unlock your Windows Phone 7 in justa few steps. This so called “Unlocking”, allows you to sideload application for testing purposes that would otherwise cost you 99$ per year! This app is safe as you can lock your device whenever you fell it’s necessary.
To unlock your Windows Phone 7, connect it to your computer via USB cable and run the zune software. Now run ChevronWP7 and follow the instructions and you are done!
Download ChevronWP7 from here.