I've been keeping an eye on the ShipBuilder PAAS project - the minimalist Heroku clone written in Go. It is starting to look quite promising.
Quoting jaytaylor's comment  from below:
> You may be interested in checking out ShipBuilder - it
> is an open-source Heroku-clone PaaS.
> ShipBuilder is written in Go, and uses Git, LXC and
> HAProxy to deliver a complete solution for
> an application platform-as-a-service.
> http://shipbuilder.io 
> https://github.com/sendhub/shipbuilder