Now you can unlock Windows Phone 7 without Marketplace developer account. Chevronwp7 manage to develop this unlock tool for Windows Phone 7.
Chevronwp7.exe is just simple executable file to unlock Windows Phone 7 devices. Just connect your WP7 device with computer and do few click to unlock the device. This unlock tool is safe and you can re-lock your WP7 device again if you want.

Download chevronwp7 executable file and Unlock Windows Phone 7
Mirror-1: http://www.multiupload.com/4T7AYFWLSZ
Mirror-2: http://walshie.me/ChevronWP7.exe
In case of any error read official notes below or leave a comment.
Official Notes
- If you’re encountering a connection error (you don’t have the Windows Phone SDK installed), try download/install the following registry key and restart your machine then try again
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\WindowsPhone\ProxyPorts]
“DeviceReg”=dword:000069C5- Minimum supported OS: Windows XP SP2
- Please ensure your device has a “full sync” relationship with the Zune client, not a “guest” relationship
As this is our first release, you may run into issues. Please let us know in the comments if this tool worked/didn’t work for you (with relevant system information).
Expect more goodies/tools to be released in the near future.
We look forward to what the broader community can do with this.
– Rafael Rivera, Chris Walsh, Long Zheng
Hey I am using windows phone 7.5 (Samsung omnia w 8350) plz guide me how to unlock it from my OS: Windows 7. Please help me out, tried the instruction provided by you but facing an error, could not connect