Component video can handle 1080i with no problem. That's what I use from my Mororola/comcast box to my Toshiba.
The problem arises when your source component manufacturer decides to force one to use HDMI, such as upscaling DVD players seem to do.
Technically, there's no reason one cound not pass 1080p via component either, but it's somewhere in the specs that it's not allowed. Ergo, you'll not find a component that passes 1080p via component, or at least I can't think of any.