Argh!  I just spent the last hour trying to figure out why I can't configure a Mule UMO (mule-descriptor) using Spring.  I ran into a couple of issues, firstly if you specify a container-context for your bean the life cycle interfaces (like Startable) are ignored.  Next I tried using a mixed Mule-Spring config file, putting the property injection declarations directly in the mule XML file, but I kept getting the following SAX error:

The content of element type "mule-descriptor" must match "(inbound-router?,outbound-router?,response-router?,interceptor*,threading-profile?, pooling-profile?,queue-profile?,exception-strategy?,properties?,bean*)".

Not being that familair with DTDs, what I didn't realize is that the comma between element declarations (as in the error message) means that the sub elements must be declared in the XML file in that order.

Big, fat, DOH!