Drupal 7 / drush / OS-X setup tribulation
Note to self:
When setting up a MAMP stack on OS-X with the intention of installing Drupal and drush, avoid at all costs the temptation to give the webserver root directory a name in mixed case.
The tendency for OS-X to ignore or respect the character capitalisation depending on circumstances may give you a world of pain when running drush commands from a terminal session.
Particularly it may appear that when drush bootstraps Drupal to execute a command, it is trying to
include PHP scripts twice, throwing function redeclaration errors as it does so. Horrid.