He is using them.
Also, EC2 just came out with better options.
And they *ARE* working on EC2 being able to support Static IPs.
They now have the original offering, 1 Processor, 1.something GB of memory 160GB of storage.
Now they have Large and Extra Large Host offerings.
Seems pretty cool. But, as in regards to static IPs, if you used some type of dynamic DNS hosting... this wouldn;t be a problem.
Though... it would suck fo rmail.