I develop dektop applications, web applications, and mobile applications. But many times a solution doesn't fit completly within the boundries of those three types of applications. There are solutions in which a desktop front-end interacts with a web back-end, or a mobile device communicates with a desktop, or in which all three work together for a common purpose (an excellent example of such a solution is Exchange, Outlook, and Pocket Outlook). Microsoft already provides solutions for making applications that interact with each other across process boundries, machine boundries, and even across different operating systems.
I've written a few articles on CodeProject.com that for the most part are isolated from other systems. The projects and the example code are about Windows Mobile and run on Windows Mobile devices. I am about to expand the types of solutions about which I write to solutions that cooperate with other devices (the other devices being servers, desktops, and potentially other Windows Mobile devices). The articles aren't targetting webservices, WCF, or interprocess communication per se though those technologies may be used within the solutions. Microsoft has alread done an excellent job of laying the ground work for Interoperability and thedeveloper only needs to use it. These areticles are targetted at tacking the technologies that we already know to exists and demonstrating new ways of using them.
I know that doesn't give a clear idea of what these new articles will cover, but you won't need to wait long to find out. I've already got the code for my next article written. With a 4 day weekend quickly approaching I plan to use one of those days to complete the article for the code. It will be for an application to make desktops and windows mobile devices cooperate in a new way.