If you want to do development on your phone and don't want to register for the Marketplace you have an alternative to paying the full 99 USD to be able to deploy to your phone. You can also register with Chevron Labs 10 USD to get deployment abilities. For the 10 USD fee your phone is unlocked and ready to run your own applications. When you are prepared to deploy to the Marketplace you will need to do the full 99 USD registration, but until then this is a nice start.
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Tags: Windows Phone