The notion that PaaS exists solely «in the cloud» as a discrete environment of developer services is hampering the maturation of enterprise PaaS.
The three most common answers to «give me an example of PaaS» are: Force.com, Azure, Google. I didn’t even need to do an unscientific Internet survey to nail that one down.
These are certainly fine examples of PaaS, but they are not necessarily examples of enterprise PaaS solutions. While off-premise PaaS offerings do address many of the same challenges being faced by enterprise operations today, they do so in a way that makes integration and control – not to mention the measurement and monitoring required by developers – nearly impossible.