PHP project structure survey
As Drupal is in the process of considering how to restructure code to best leverage the PSR-0 standard, I figured it would be wise to take a quick survey of how some other major projects organize their code bases. This is not a complete rundown of every project, simply roughly comparable notes for those areas Drupal is currently discussing. I am posting it here in the hopes that it will be useful to more than just Drupal.
Note: This is based on one evening's work of poking around. If you work with one of these projects and have more information to provide or want to correct a mistake I made, please do so in the comments!