Referencing Clayton Christensen, Nielsen explains that whenever a technology becomes a commodity the next layer begins to innovate, and that’s what he’s seeing with Platform as a Service (PaaS) players.
Nielsen led a session at Silicon Valley Code Camp, where he reviewed all the different PaaS solutions. What PaaS does, he says, is automate all the muck of infrastructure and IT and place it in the cloud. If you want to move your application somewhere else, you simply install the PaaS on another cloud infrastructure provider.
Nielsen has a whole list of the PaaS providers on his wiki. But when I asked him to name his favorites he called out AppScale, the open source version of AppEngine and all the services like Cloud Foundry, which allow you to run multiple languages such as Python, Java, and Ruby on Rails in the same instance and so let the services they provide all be available to the other programming languages.