Pieter Kokx has posted a proposal and needs feedback. Zend_Db_Schema is a component that provides abstraction for DDL statements. You can find the proposal here.
Graham Anderson writes a very interesting proposal; If you are interested in an implementation of storing and retrieving hierarchical data as a nested set, please take a few minutes to review my new proposal[1].
I dusted off some old code and poked and prodded a little until it behaved somewhat as expected, there’s a functioning prototype on GitHub[2] with some basic instructions in the README.