We have an exciting breakthrough for the Windows Phone 7 homebrew community – the ability for anyone to unlock a WP7 device without a Marketplace developer account. Unlocking allows the sideloading of experimental applications that would otherwise can’t be published to the Marketplace, such as those which access private or native APIs.
“We’ve taken the pain out of the process involved and put together a super simple executable that will allow anyone to unlock any WP7 device on the market using a USB cable and just a couple clicks.”
This tool is completely safe and reversible for the phone. (The app even allows you to relock the phone.)
v1.0 download mirrors:
More info and how-to guide: http://www.chevronwp7.com/