OK, Problem solved ... I think ;)
The solution was to supply an execute parameter to the ajax component, reexecuting the inputText field.This helps running this example. But still I don´t know why it was not working ...
<h:panelGrid>
<h:inputText id="input" value="#{ajaxController.text}">
<f:ajax event="keyup" render="text" execute="input" />
</h:inputText>
<h:outputText id="text" value="#{ajaxController.text}" />
</h:panelGrid>
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