Source: http://en.wikipedia.org/wiki/Wheel_and_spoke_model
The Wheel And Spoke Model is a sequentially parallel software development model. It is essentially a modification of the spiral model that is designed to work with smaller initial teams, which then scale upwards and build value faster. It is best used during the design and prototyping stages of development. It is a bottom-up methodology.
New system requirements are defined in as much detail as possible
A preliminary common API is generated that is the greatest common denominator across all the projects.
A prototype is given to the first program where it is integrated into their needs.
Feedback is gathered from the first program and changes propagated back to the prototype.
Each new program will use the common prototype
The final system is the amalgamation of common features used by the different programs
Routine changes and additions are eventually seen by every program that uses the common code