As far as I can tell your name is color coded to the rank you are, but I don't think however you can type in color.
I noticed in like the sample motd some messages are preceded by something like this:
§b
This seems to be the color code notation, but I don't see a way of getting that into chat as the client doesn't like copy/paste or alt codes.
This could be something built in, but would probably be more suitable for a plugin of some sort.