<Disclaimer>This is personal notes of what I retained during the session. This can be incomplete, partially right or wrong. It is just  part of the notes I took and what retained my attention. Nothing prevents the user to get more information on their favorite web site.</Disclaimer>

In this presentation, Aaron Skonnard starts by making the difference between an ESB and an Internet Service Bus. The former provides Messaging Fabric, Service Registry, Naming and Access Control accross the enterprise departments and allows interoperability and connectivity between the applications.
Internet Service Bus does the same thing, but, in the Cloud.
During his first demo, Aaron starts a console application registering and publishing into the Cloud a service running on his own laptop. It was then possible to the attendess to access a feed representing the service proposed located on the laptop.
Anyway, there are several challenges : IPv4 first, making an IP address shortage that is present. Another challenge is that machines are behind firewalls and using NAT. And, last but not least, there are a lot of bad guys out there. All of these challenges make that it is really difficult to have a bidirectionnal connectivity.
Some solutions exist, such as Dynamic DNS, UPnP, or even port opening in firewalls. This last option is never well accepted by IT Professionals with good reasons.
Basically, we can see the Service Bus as an enabler to bring the Cloud into the enterprise (integration).
Then, Aaron focuses on three services offered by the Service Bus : Naming, Registry and Messaing Fabric.
On the Naming side, a solution name is linked to a customer and a set of service. It offers a hierarchical naming which offers the possibility to browse to a particular service. Basically, we have addresse like scheme://servicebus.windows.net/solution/name/name . But, this could even be scheme://solution.servicebus.windows.net/name/name with, maybe afterwards, the possibility to extend the URI on both ends.
Registry is a layer over the naming system. It offers a programmatic access for discovery and publishing into the Cloud. In other words, when a service is shutdown, the endpoint disappears from the registry. It is possible to access the registry using a simple internet browser. Indeed, the registry is exposed as nested ATOM feeds.
The Messaging Fabric uses the programming model of WCF and provides a family of bindings that corresponds to the WCF bindings.