Maturity Models

I was introduced to maturity models through the Capability Maturity Model (now CCMI). Recently, there has been an explosion of maturity models. They all follow a similar path:

1) Undefined
2) Defined
3) Managed
4) Optimized

Depending on the process they may be called different things and they may be broken down into finer detail but they all begin with chaos and end with continuous improvement.