I haven't tried it. It does look like a great service. One thing, however, that I don't think it provides is auto-scaling (i.e. provisioning additional servers

I haven't tried it. It does look like a great service. One thing, however, that I don't think it provides is auto-scaling (i.e. provisioning additional servers or removing servers when they are (not) needed). If they were able to provide that, I think it would rule out a need for Heroku completely.