The creators of a jailbreak for Windows Phone 7 have pulled their creation after a stiffly worded letter from Microsoft ruined their day.

According to Ars Technica, ChevronWP7, was released last week. It was billed as a tool to allow development and installation of Windows Phone 7 applications on any phone, without having to go through the Microsoft approval process. As far as tools go, it was not well-received.  Some felt it was a step towards enabling application piracy on the new platform.

ChevronWP7's developers wanted homebrew development which meant that people could write applications without having to pay $99 to Microsoft for a Windows Phone 7 Marketplace account, without distribution via Marketplace, and without having to submit their software to Microsoft for validation. Next they wanted the software to be able to be developed by residents of those countries that are not currently eligible for Marketplace accounts.

But the ability to load custom applications without going through Marketplace is what raised piracy concerns. Microsoft is a little worried that with the OS new,  piracy for that platform could send third-party developers running for the hills. ChevronWP7 enables pirates to load applications without going through the official channels.

The ChevronWP7 developers claimed that their tool did not enable piracy as it did nothing to take down theDRM imposed on applications downloaded from the Marketplace. But really ChevronWP7 applications could do anything. An application developed and deployed with ChevronWP7 could modify the operating system in some way to allow anything a pirated wanted.

The Imperium was quite low key publically about the jailbreak. It just muttered stuff about breaking warranty and it could brick your phone. However it seems that behind the scenes it released the hounds.