According to their manuals, all 8 HD models of STB and DVRs have both HDMI and coaxial cable outputs. However, I know personally that my old model 6416 is an HD DVR and does not have a coaxial cable output. I used to use a composite to coaxial cable adapter (supplied at the time of install, but also available for about $20) before I got a new TV. So the answer is yours will probably have both, but may not have coaxial cable output.
Or did I mis-read the question? If you were asking if they came with an HDMI cable, the answer is that the installer will usually supply all the necessary accessories to get you up and running. When I got my first HD box (self-install) they sent me an HDMI cable with it.
All the HD boxes support HDMI then. They also currently all support coaxial COMPONENT connections, although the movie industry wants to make component supprot of hd go away (they succeeding in making it go away with blu-ray players now being manufactured).