I've been talking on twitter about working on some stuff involving 2D soft shadows. I was going to write a long blog post about how I got 2D soft shadows working in XNA using the GameDev article in combination with Catalin's implementation and Christian's implementation in D. However, trying to write the post, I wasn't sure if I could make it any clearer, as I'm not sure if I understand it completely myself.
So, instead, I'm just going to post the XNA port I made almost directly from Christian's D implementation without much comment. I will say that, instead of using the images that both Catalin and Christian are using, I've move most of that into shaders. This isn't necessary, but it's in preparation for some other stuff I want to do later with this project.
So if you're interested, my XNA implementation is here. Enjoy!