Here is another idea for the jacket/ bag combo. Looks pretty nice compared to a lot of the other designs for the same type of thing. So who is going to be the first to make one?

http://thelook.today.com/_news/2012/03/26/10780437-designers-sleeping-bag-coat-transforms-and-warms-detroits-homeless

It's a cool idea, and I applaud the designer's ambitions and her interest in outreach. For backpacking, though, from a function standpoint, I have the same misgivings about this design as I do about all jacket/sleeping bag combinations. People need more insulation at night, when temps are lower and one side of their body is in contact with the ground. Any sleeping bag warm enough to sleep outside at night would be too warm to wear as a jacket unless there is extra night-time insulation that can be removed. The traditional mountaineering combination of a heavy jacket and an "elephant's foot" sleeping bag does just that.

On the other hand, the conditions that would make the jacket/sleeping bag combination ideal are warm(ish) nights and cold days, which might be exactly what a person living in a shelter in Detroit experiences in winter. I could see these jacket/sleeping bag combinations being popular, even if they don't take off among backpackers.

If the jacket has good ventilation that can be closed up for "sleeping bag mode" it could alleviate the problem you mention (which I completely agree with).

For example...my running jacket has mesh in the armpits and another panel in the back (shoulder blade area) that can be opened or closed to keep my temperatures regulated very well in the winter.

I agree with Colin's comments.

With temps in the upper 20sF I found it impossible to stay warm even with "The traditional mountaineering combination of a heavy jacket and an "elephant's foot" sleeping bag".

I tried it around 1970 for one night. I had an Eddie Bauer bag rated at -20F and the warmest down parka EB sold at the time. From the chest on down I was fine (covered by the bag) but I could not keep my upper chest, head, arms and shoulders warm enough to sleep for long. I just about tore out the bottom of the bag trying to get my whole body down into it. Very long night. Very good lesson.