<p>There are some updates with .NET 3.0 concerning how to create and use add-ins for your own applications. I read about some "<em>pipeline</em>" you have to create for the communication between add-in and host-application but couldn't find further information about it.</p>

<p>How would you made an add-in functionality in an application with .NET 3.0/3.5?</p>

<p><strong>Additional information if necessary</strong>: The host application is made with WPF and some general functionality. Each add-in should add a own register-tab to a given container with their own content (buttons, textfields, ...) and methods to extend the host-application.</p>

In addition to
Daniels
codeplex link, Jason He also has a nice wee series on using the System.AddIn namespace when developing Paint.NET starting here -
http://blogs.msdn.com/zifengh/archive/2007/01/04/addin-model-in-paint-net-1-introduction.aspx