Update: Shortly after I posted this article, Peter Henry noted that he had a very similar article out already. Here is the link to it – it has good additional information – check it out: http://www.pchenry.com/Home/tabid/36/EntryID/389/Default.aspx

So you got your Windows Phone 7 device, you downloaded the free development tools and now you are itching to write your first “Hello World” app for WP7. You fire up VS 2010, create a quick phone app, connect your WP7 device to your development PC, select “Windows Phone 7 Device” as a target and attempt running your first app on your phone.

You will get the following message…

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You have to make sure your device is ”developer unlocked” before you can deploy applications to it. Here’s how you unlock your device:

  1. Connect your device to your PC through USB.
  2. Start the Zune desktop software.
  3. Start the “Windows Phone Developer Registration” software.

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  1. At this point, provided you have a developer account (which you get on http://developer.WindowsPhone.com) you can register your device. Once registered you’ll be able to use it for development purposes.

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Easy! (not necessarily straightforward though :) )