When presenting Web Services and interoperability, I like to emphasize how Web Services are not tied to any underlying transport or protocol.  WSE 2.0 is a fine example of this, and can be extended by creating your own custom transport.

To demonstrate, I put together a sample showing how IBM MQ Series (aka WebSphere MQ) can be used as an alternative transport for Web Services.  The sample uses the following URL structure:

soap.mqseries://localhost/QueueManager/QueueName

(where localhost is the endpoint connection to MQ Series, QueueManager and QueueName specifies the end point)

You can find the sample here.  The sample requires CSD05 or later of IBM WebSphere MQ 5.3 (I built this using CSD07).

There are some limitations:  Today, it only supports one way calls (I'm working on a promiscuous mode where multiple subscribers can decide which message to pickup), and the MQS endpoint has to be localhost.  This sample is unsupported, but I am interested in any feedback.

For other transports, you should also check out:  Hervey's UDP transport, Steve's SMTP transport and Roman's MSMQ transport on CodeProject.