>Google et al. do essentially run their servers on EC2.
If by EC2 you mean "bunches of servers", sure.
On GoGrid you can buy cloud servers, or you can rent dedicated servers (and you can intermix the two). The latter are quite a bit less expensive for a given quanta of resources, while the former obviously offer greater dynamic flexibility (with a significant premium).
Actually considering the terrible I/O rate of services like EC2, dedicated often offers a dramatic advantage.
>They have a whole pile of virtualised servers they can turn on an off by the minutes.
But they don't. So they use none of the upside, and have all of the downside. Yay!