I take issue with the offhanded remark that Heroku is cheaper. The whole point of Engine Yard for me is that it is a straight markup on AWS services, and you can run whatever you damn well please on your instances. With Heroku A and B might be free, and C is an add-on costing an arm and a leg, even though it's all open source software requiring the same amount of resources.<p>The way I see it, Heroku is ideal when you are small, Engine Yard is good up until medium size, but if you ever hit real scale, the overhead is not at all worth the benefit.
Nit:<p><i>[Engine Yard is] really easy if you have a public github repo, but anything other than that starts to get "more complicated" quickly.</i><p>You can also hook it up to a private Unfuddle repo, and I would assume private github repos too.
If you use GitHub, EngineYard is pretty easy and smooth to use as well. Just git push, then redeploy. The only pain is creating custom recipes for stuff they don't support. But I do like the ability to SSH. I can go in, run scripts, delete files, etc. Heroku seems too much of a walled garden.