There are two write-ups on my blog about these and the Project templates. These Item Templates, in combination with the Project templates, will allow you to create and compile Mono based projects in Visual Studio.
From the original post:
"The goal was to get some Mono project templates working with Mono assemblies and the Mono compiler in Visual Studio. The trick was to do it in a way that would be able to survive upgrades of Mono installations. I think I pulled it off. :) The end result is a series of project templates that you can put in your \My Documents\Visual Studio 2008\Templates\ProjectTemplates\Visual C#\Mono directory that will give you some New Project options"
If you have any comments, questions, etc about these, please leave them on the blog for now. As we get into more Mono development, we'll create some forums for that.