Nicholas Allen has some excellent posts about WCF where he gets into a lot of the nitty- gritty and explains things like transport security, encryption and hashing, and so forth.
One of the coolest things that I see WCF offering is the decoupling of the transport and encoding mechanisms away from the service. With WCF the focus can be on what services to provide and their internal implementations, leaving the question of how to expose them as a deployment issue. Transport and encoding options are combined in the notion of a binding and there are a number of out-of-the-box options to choose from as detailed by Nicholas.
After you have developed your service in WCF and it’s time to deploy your service to the enterprise you can choose any number of these bindings, combine them to offer multiple ways to consume your service through multiple endpoints, and/or develop you own custom transport and/or encoding to make you own custom binding.