Yes I Can!

How to Jailbreak Windows Phone 7 with ChevronWP7 Unlocker

The developers (or call them wp7 hackers) behind ChevronWP7 are well known Rafael Rivera, Long Zheng and Chris Walsh who have been reverse engineering Window Phone 7 OS from the day it was launched. The first release of ChevronWp7 may have some hiccups but should work on every smartphone powered by Windows Phone 7.
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Step 1: Download and install the latest version of Zune desktop software for Windows.

Step 2: Download and install the latest version of Windows Phone SDK, OR simply download this registry key and execute it on your Windows machine with administrative access. This registry key will add the following entry:

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\WindowsPhone\ProxyPorts]
“DeviceReg”=dword:000069C5

Step 3: Now connect your Windows Phone 7 device (Samsung Omnia 7 in my case) with your PC via USB.

Step 4: Start Zune software and sync your device. Make sure your device has a “full sync” relationship, and NOT “guest” relationship with the Zune software

Step 5: Download ChevronWP7 (Windows Phone 7 Unlocker app) and run it.

Step 6: Before unlocking, make sure your device is not locked with a PIN.

Step 7: Check “Ensure your phone isn’t PIN-locked” and “Install certificate on phone using Internet Explorer at http://chevronwp7.com/cert” options, and then click on the “Unlock” button.

Step 8: That’s it! your phone is now unlocked ! You can now install (sideload) any third-party WP7 app without requiring a Marketplace developer account.