I'm seeing a lot of comments talking about "just get a {VPS, dedicate box, Amazon, etc...}". I think people are missing the point. AppFog is trying to take all the "hard" work out of SysOps. Think Chef on crack, you are paying for their pre-configured infrastructure from the top down.

Their idea is provide a powerful, scaleable platform quickly and easily. Their mentality is called NoOps (http://blog.appfog.com/what-is-noops-anyhow/). It's a cheesy marketing term, and pissed a lot of people off, but it's pretty spot on for what their service offers.