Now you can jailbreak our for our HTC 7 Trophy, Mozart, HD7 or any other Windows Phone 7 device with ChervronWP7, with wich you can download applications to your device, without using Marketplace.
ChervronWP7 is compatible with Windows XP SP2 and higher. You can use it to unlock a Windows Phone 7 device. Now all the applications that have not been approved by Microsoft for MarketPlace, can be installed them.
Is a very new and has not been tested much, so they also can be a bit dangerous for your Smartphone. But if you’re brave and want to try, here’s a link to know how it works, with all the details.