Since working with EnterpriseServices (ES), I have found some of the nicer features that are available through COMPlus 1.5 (on Windows XP and Windows Server 2003 ONLY). A couple of noteworthy options:
1. COMPlus Services without Components. I can implement select features of COMPlus (such as transactions) without all the overhead of invoking a full-blown .Net class derived from ServicedComponent. I am still determining how useful and viable this is in a large distributed environment.
2. IsPrivateComponent. A property (attribute) that allows me to mark a component as private (within a Server application). This private component is only callable within the Server application. Previously, in COMPlus 1.0 (Windows 2000), all components had to be public to have access to COMPlus services, which meant that these components could be activated from other applications.
Some other COMPlus 1.5 specific features are noted in the .NET Enterprise Services and COMPlus 1.5 Architecture article.