Sealed Helium
While the concept is commendable i also share your concern about the helium part! You can't just store the heat in the drives there must be a way to transfer it out of the "Hermetically sealed enclosure" else we might be having cases of exploding HD in the data centers!
The good side is that we are assured (assuming that there is another explanation of how this is supposed to work) of having larger capacity drives to temporarily satisfy our insatiable need for larger, faster, cooler and tinier drives. Fantastic though that they are pushing the envelope on this.
Regards