Microsoft is answering some questions about the Xbox360's HD-DVD drive in another forum. Their component video output will play HD-DVDs in 1080i. As Steve indicates above, that is as far as the spec goes (EIA/CEA-770.3-C). However the XB360 will do 1080p through it's VGA output, and there will be no HDMI with the current system.
If your question is more oriented towards 'Can' component handle 1080p? Then the answer is yes. Pretty much anyhting VGA can do, component is capable of.