>I suspect that a typical .NET assembly is a sophisticated COM object but i do not know much about it...

Try these:

http://msdn.microsoft.com/msdnmag/issues/1200/com/

http://msdn.microsoft.com/msdnmag/issues/01/03/clr/default.aspx

http://msdn.microsoft.com/netframework/using/understanding/interop/default.aspx?pull=/library/en-us/dndotnet/html/entserv.asp

and if you're really curious and have some spare time:

http://msdn.microsoft.com/netframework/using/understanding/cli/default.aspx?pull=/library/en-us/dndotnet/html/mssharsourcecli2.asp

-Mike