I was actually thinking about elastic AWS instances when I wrote that. IIRC they're meant to be spun up and then shut down as a service's demand varies.
VPS providers are already overprovisioned anyway, so they have less idle hardware to begin with.
Isn't that really expensive? Far more expensive than just keeping a cluster running 24x7? I think the much bigger cost here is shelf space and the hardware, and so the retail price isn't impact much by the cost of power.
For the record I like the concept and hope it becomes a lot cheaper over time.
VPS providers are already overprovisioned anyway, so they have less idle hardware to begin with.