The lack of multi-room viewing is not specific to Verizon; it's a licensing issue.

I can't speak to Verizon but this seems to be an industry-wide issue. I am a TiVo user, I've got two SD boxes and an HD box and TiVo has the same issue.

Esssentially it's because CableLabs has not approved the Multi-Room or TiVo to Go features with the TiVo HD box. It is almost certainly an issue with the cable companies and content providers dragging their feet on approval of the copying of HD material between devices.