I was surprised to read this article by Steve Hoffman, linked to by Joe McKendrick.
He seems to be conflating the problems solved by service orientation with the problems solved by constructs such as ESBs.
He is correct to imply that you cannot easily consume services if they're all exposed using different protocols and transports. However, that doesn't mean having multiple invocation technologies in an enterprise is a bad thing. Sometimes you have no choice but to let pragmatism trump purity. Rather, it's an argument for a separation between the logical description of the services offered and the physical details of how to invoke them. The enterprise service bus is the construct to which you delegate the problem of doing the switching.