Christian Lerrahn has started a project with the goal to describe the core of TYPO3 more tutorial-like. he says that the current documentation is more like a reference (yes that's it). He wants to go through the code and look what it does and how. The results of these discoveries will be written down in a document.
He started a Wiki page for the project and looks for people out there that are willing to help him.
[Thanks to Thomas Hempel from whom I copied the text]