My thought exactly .. where did the grid go? It was all the rage a few years ago.
Anyway, six minutes or not six minutes. An EC2 image, once shut down, is available to put back in production immediately, so I don't agree with Fitz' prediction that it'll take almost five years to get to 6 minutes intervals. As soon as Amazon realizes this usecase, why wouldn't they slash the billing interval? It would seem that our hours is chosen because it's easier to manage, and their initial use case was host of apps with peak periods - not one-off parallel tasks.
While it isn't seconds, 6 minutes would be a lot better than an hour.