Even though it is a start up company, Sensinode has done wonderful work on IoT on the entire technology path starting from radio, protocol stack and API with graphical environment. They are already providing evaluation code/stack; I hope ARM will go further than that.
Yes, ARM will be a major player in the PAN and IoT implementations, as the protocol stack will be demanding processing power in every next coming versions of implementations, and being modular architecture of the processors from ARM it will be the first priority for the developers who are seriously planning for a large productions of IoT enabled products.
IoT is the "next big thing" that has been growing for a few years, but is ready to breakout mainstream. For example I have an app on my phone that can turn on and off the security system at my home. So if I go to work and worry that I forgot to set the alarm I can simply look at the app on my phone to know the status and activate it if necessary. IoT is already here, but companies like ARM will certainly help make it a household term among the general public.
Sounds like ARM is pretty much solid in investing for the IoT space. I did not know the news of Linear Technology buying Dust Networks, this is a surprise to me. Good to see that Linear has been offering the wireless sensor solution for low power, energy harvesting kind of applications.