I have only started my testing on 1.2RC1 but I have an app that uses components and it died out of the gate.
It sounds like it is having problems finding the template. I see this in the rendered view:
Missing template script/../config/../app/views/front_end_header/front_end_header/front_end_header.rhtml
That is the view for the component. The component's controller has this line in it:
Still, removing that doesn't fix anything... Still, my component views seem to be broken and from what I have read about depracations, this isn't one of them.