In a recent Paul Maritz talk at GigaOm Structure conference, he referred to PaaS as "a cloaking layer for clouds." This is an elegant definition for a rapidly expanding market of add-on cloud services.
If Cloud 1.0 is a set of servers in the sky (think Amazon EC2), then Cloud 2.0 is a layer of services that hide the complexity of developing, deploying and managing applications in the cloud (think CloudFoundry).
- Dev/test environment: WaveMaker pioneered the market for cloud-based development of standard Java applications. In addition, simply virtualizing the provisioning of servers has huge value for development and testing purposes. Today, this is a major driver for developer adoption of cloud in general and PaaS in particular. I have talked to CIOs who claim that over 30% of their resources for new projects goes into provisiong and managing the dev/test environment.
- Scalable application deployment: Amazon EC2 has made its mark by providing a highly scalable data center in the sky. Zynga uses Amazon as a safety net when it has no idea how popular one of its games will be. Once Zynga has a handle on demand, they move the game over to their own data center. Just a year ago, getting this kind of scaling required detailed understanding of cloud architecture and a whole lotta scripting. Now it's as easy as "vmc push --instances 8"!
- Resilient application deployment: infinite scaling is great, but what happens when a network configuration error brings down in your infinitely scalable data center? In that case, having a PaaS service that automatically mirrors applications across multiple data centers makes a critical difference.