node.getMarkupId()
gives you the id the node will have in the html, which is often different from the wicket:id.
wicket:id corresponds to the component id in the javacode (in the case of new Label("blah")
) the id is "blah".
In the generated html this might become <span id="blah12f4"...
node.getMarkupId()
will return "blah12f4".