Windows Phone 7 is "finally" jailbroken! ChevronWP7, the unlocker tool, works with every WP7 phone and allows for the side loading of apps, the use of private APIs, and access to low level functionality.
Basically, it unleashes your WP7 phone.
Source:
http://gizmodo.com/5699207/windows-phone-7-gets-jailbroken
