Michael Klucher writes about a Paint.NET plugin for loading and saving Photoshop files. And this plugin includes C# source for parsing the .psd format. Hmm. I wonder how hard it would be to turn this into an XNA Framework texture importer, so you could add multi-layer .psd files directly to Visual Studio without having to flatten and export to some other format first?
Just throwing this out there on the off chance some enterprising reader might find the idea as interesting as I do 🙂