Yeah, I agree with Tomi. Just stick to the core business model, dont show any implementation specific classes (controllers, delegators,facades,daos etc). If you are still inclined to show the entities and session, show them as <<stereotypes>> in your class diagram. eg. Customer can have a <<entity>> stereotype attached to it.
The only thing I am very tempted to show are the adapters to the outside system. Am trying to figure out where they would fit in the class diagram, or I might just show them standing alone in some corner of the class diagram
parag