I found this in an email I sent to in May.  This would definitely be something to check out if you develop in COM+ with .NET.  Deployment in most environments will be simplified, since registering with component services is usually only done by a sysadmin.  Check out Early and Adopter and MSDN Library for more info.

Services Without Components

On Windows 2000, if you want to take advantage of COM+, you have to package your managed code into a class derived from ServicedComponent that is registered with component services. This forces developers who want services such as transactions to factor their class designs into transactional and non-transactional classes.

Windows Server 2003 allows you to programmatically enter and leave a Service Domain by making a pair of API calls. When your code executes within the service domain, it behaves as though it is in a serviced component. Services such as transactions will be applied to your component automatically. This scenario makes it possible to build a component that uses transactions for some methods, and does not have to inherit from ServicedComponent.