Microsoft has released a tool that they developed inside their consulting division. They created the tool to help their customers and now they are starting to make it more widely available.
The version they released is version 6.2, which indicates that it's already been through the paces of real-world use. It comes with decent documentation, a management UI, a universal service tester, and the runtime that hosts the virtual services.
It's built on WCF and has a deep understanding of how WCF works. This is important because it differentiates MSE from other products on the market. Conceptually, the engine is kind of like an ESB and kind of like an SOA governance product.
It's like an ESB in that you have a way to connect multiple consumers to a suite of services and redirect them wherever they need to go within the bus. It has some light transformation capabilities via XSLT transforms that are most useful for versioning services.
It's like a governance suite in that you can apply policies to a service to enforce certain requirements. The policy enforcement is not well documented yet, so I'm not sure how much it can do. They provide some examples that appear to be pretty flexible and powerful.
It's build on top of a very nice service repository, which lists the service endpoints, their endpoints, their WSDL contracts, and their bindings. It appears that they might integrate this with UDDI at some point. If not, the repository is built as a web service, so we can use it directly.
I've installed it locally and so far I am very impressed. It's not a silver bullet, but there is no such thing. It is a sweet tool for helping us with our environment.