There are multiple implementations of it, heres the canonical one: https://github.com/ddollar/foreman And heres a go version that's easier to install and use: https://github.com/ddollar/forego
edit: A really simple and effective process manager is foreman and its procfile format. I like the golang version of it (simple single binary with zero dependencies): https://github.com/ddollar/forego or https://github.com/mattn/goreman
http://nsq.io/overview/internals.html
The service you are thinking of might be https://github.com/ddollar/godist
You can see the download links on https://github.com/ddollar/forego use it.
EDIT: It really seems that they are going down that route. They are also working on a Go implementation of Foreman here: https://github.com/ddollar/forego