If you don't like the idea of relying on RedHat to play with this tech, remember that it is Open Source. Download it, use it, heck make a business that builds on it.
(I will say though: they make it extremely easy to get started and I really like using OpenShift so far. I've never used Heroku, but if it's this user friendly i'd definitely have used it before... Why don't they have a free offering for people to test out the service?)
I know of people who deployed prototypes and even production work for clients to Heroku (I did once too ;-)). Quite a few people run Jekyll blogs on there long term for free as well. It's pretty amazing what you can get out of a single dyno for something that's not high traffic (i.e. most apps).