Well, I'm working on a startup that's based on Open Source software, but right now everything is funded out of my pocket, essentially. We plan to sell subscriptions to the official, certified, released version(s), ala Red Hat, as well as offering a SaaS based on our offerings, but we don't have paying customers just yet.
There's at least one open source project[1] out there, something I think Red Hat may actually be involved with (or behind) for managing subscriptions and what-not. We haven't deployed it yet, as we aren't yet at the point of having paying customers. And if we signed a deal tomorrow we'd just keep track of things manually in the interim.
As for distribution... we're working on our own homegrown "customer portal" which will deal with downloads and what-not, as well as other "customer stuff".
