Indeed let's do that. At our weekly meeting yesterday, there were 18 engineers in the room. Every one of them is working hard to make this feature happen. My role at this point is mostly to kibitz, and help with the field testing.
HDR+ is available only on Nexus 5 and Nexus 6, because only those devices currently fully support the Camera2 API, which is required for HDR+. This will gradually change, and more devices will start offering it.