At the Haskell Implementor's Meeting in 2003, Isaac Jones gave a talk about this project. You can view the slides for that talk here. If you are interested in software archaeology you can get the corresponding example implementation.
There are other old releases here.
The original proposal (or pdf) (updated August 1, 2004) for the Library Infrastructure Project. This served as an explanation and specification.
There are also previous versions of the proposal:
Isaac Jones, 2005
The Haskell Cabal: a common architecture for building applications and libraries