As far as I know (i.e., according to some professors I've spoken to), transistors in devices with extremely long battery lives, such as hearing aids and watches, are typically operated in sub-threshold in order to conserve power. Of course, these devices are also typically not speed-critical. A lot of biomedical applications probably fall under the umbrella of requiring low power (for battery life and/or thermal reasons) and not requiring high speed, making the application a natural fit for sub-threshold operation.

Satellite communications is expensive (and naturally the market is smaller than terrestrial phones so even at the same cost the price per subscriber would need to be greater). Higher data rates require greater SNR and therefore larger antennas. Receivers also need to consume more power to acquire and process a low SNR signal. Perhaps they can improve these things incrementally, but they're kind of fundamental to the nature of their service.

They do. http://en.wikipedia.org/wiki/Silicon_on_sapphire

I did some basic simulations in Ngspice using Kjwaves as a waveform viewer and it worked pretty well for my purposes (I did end up editing a little of the Kjwaves code to fix some issues I had with autoscaling axes, but it was pretty minor). The interface is comparable to using HSPICE + Awaves in my experience. http://ngspice.sourceforge.net/kjwaves.html

The bios at the end of the paper clearly state that both the Ph.D. student and the professor are from USC, not UCLA.

When it stops being profitable to continue scaling transistors. The reason we scale is because it makes chips cheaper, faster, just plain better, meaning Intel and AMD (and others) can sell it for lots of money. If scaling no longer achieves that goal, you'll see it end in a heartbeat (just like you saw clock speed ramping come to a halt once it wasn't selling like it used to).