I remember one of their chief expenses a while back was under-utilization - they need enough capacity for the christmas rush etc, but it does unused during the slow times. It looks like they're letting other people pay for their under-utilized computing power and also deal with the utilization problem themselves beneath the 1 hour mark.

Every now and then I wonder if there's a market for someone to do something like app engine on EC2 in order to cater to the 10 minute job market.

With something like that you could just leave the EC2 instances up and just swap jobs in and out, track the time and charge some small markup for the convenience.

As long as the demand was there you'd just have to bring more instances up in peak times then let them die off one by one when things slow down. Put a nice client side API on it and use Amazons billing API so the client can handle all of their computing payments at the one point and you're ready to go.