True that also others can register. Their mailing did mention "As newsletter subscribers, we want to give you exclusive early access and get your feedback" belo

True that also others can register. Their mailing did mention "As newsletter subscribers, we want to give you exclusive early access and get your feedback" below a "HyperDev Private Beta" heading. Personally, I don't think it will be Open Source, at least not soon, but who knows. I haven't seen an indication on the business model or long-term strategy - could be paid hosting for running applications with more resources (just like Heroku, OpenShift, Google App Engine and other PaaS providers), or paid add-ons for additional features (monitoring, analytics, logging, persistency, high-availability). Or perhaps it is an entry for their Kiln service, version control and source code hosting, but I'm just guessing here. Fog Creek is using different types of revenue models for their services.