Windows CE for Platform Builder/OEMs has DCOM as a module that can be optionally included. It is not, never has been, and never will be an option for Windows Mobile/PocketPC/Smartphone devices. CE's DCOM was based off of the NT4 SP5 era.
If you select the component in Platform Builder in CE 5.0, you'll get a very strongly worded security warning that begins with the words "The remoting component of DCOM will be removed from future releases of Windows CE."
We haven't solidified on the exact plans for our next release yet, but the fact that we put this comment up should be taken as fair warning. If you're creating a new project for WinCE and you don't have to deal with legacy DCOM clients/servers, you should under no circumstances be using DCOM.
The best alternative in my opinion is using "web servicy" type technologies. For server side, we have a web server and a soap toolkit. For client side we have C#, wininet, and also the soap toolkit helps there. You can also use Windows Sockets and roll your own protocol, but we think HTTP (and XML) are the future. A lot of hard problems, like authentication and encryption, have been solved at the HTTP layer already for you.
CE will continue to support in-process COM. If I removed that I'd break half the CE apps in the world and would have to go into hiding. We will also continue to support COM between processes on the same machine. Removing this would break a bunch of things, most notably popups on IE (and where would we be without popups ?:)).
A general introduction to Web Services (desktop specific, not WinCE) is available at http://msdn.microsoft.com/webservices/default.aspx?pull=/library/en-us/dnwebsrv/html/introwsa.asp.
[Author: John Spaith]