One of so many differences between Windows Phone 7 and Windows Mobile is the fact that Windows Phone 7 doesn't allow to side-load apps which means users can't install apps from a PC to a Windows Phone 7 but from the Marketplace only. However, Windows Phone 7 isn't anything different to the Apple iPhone or HP Palm webOS which are also designed to only accept apps OTA from its mobile device markets. However, following the recent registry hack which allows to connect Windows Phone 7 as a mass storage device for Windows PCs, smart developers have yesterday released "ChevronWP7", an application unlocker which allows to install apps on Windows Phone 7, without using the Marketplace.
Beside and unfortunately opening the door for software piracy, the tool has some user and developer benefits which shouldn't be underestimated at all. For instance it allows to develop (and even more important install) apps which might never pass Microsoft's Marketplace process, for instance ringtone changers to allow custom ringtones, WiFi hotspot apps to use Windows Phone 7 as a mobile hotspot, etc. Furthermore it's an easy way for developers to distribute Beta software to a closed user group of testers which don't need anymore a Microsoft Marketplace account to unlock their devices the official way.
ChevronWP7 is now available as a free download and runs on any Windows PC greater Windows XP SP2.
UPDATE: The team has pulled the plug and isn't continuing the project anymore. According to the developers, they were contacted on December 1st by Brandon Watson, Director of Developer Experience for Windows Phone 7, to discuss the ChevronWP7 unlocking tool. Through this discussion, "we established a mutual understanding of our intent to enable homebrew opportunities and to open the Windows Phone 7 platform for broader access to developers and users".
To pursue these goals with Microsoft's support (whatever it means), Brandon Watson has agreed to engage in further discussions with ChevronWP7 developers about officially facilitating homebrew development on Windows Phone 7: However, "to fast-track discussions, we are discontinuing the unlocking tool effective immediately".
To reiterate their enthusiasm to enable new opportunities, the developers have nevertheless released a Windows Phone 7 custom ringtone manager that shows off exciting platform potential. The source code has also been made available to guide homebrew developers.
Cheers ~ Arne