Unlocking a Windows Phone 7 device for development

After having worked with the Windows Phone 7 emulator for a while, I finally received my real device today (a shiny Samsung Omnia 7). I first played with it for an hour or so and then wanted to unlock it immediately to give it a spin in Visual Studio. As it turns out, this is easy, but not as obvious as it should be, and I found it hard to find appropriate help when I searched the web, so I decided to give a quick summary here.