Visual Studio makes it easy to build Web services, whether those Web services access information in Exchange or other datastores. You can expose your collaborative information using Web services, allowing other applications to get or set data in your application. This is what makes Web services so powerful: a programming model that works across many products and many platforms. When you build your applications on Exchange, you should evaluate whether exposing most of the functionality from your application through Web services makes sense. Web services provide great benefits with very little additional coding.