Today I ran into an issue where running the command:
drush status
ended with this error:
Drush command terminated abnormally due to an unrecoverable error..
Not sure what was causing this problem so I turned to Google and came across this post: http://drupal.org/node/1140842. This comment, http://drupal.org/node/1140842#comment-4526230, mentioned that they were using mobile tools, which I was, and when they disabled it, drush began working again. Unfortunately, this website was relying pretty heavily on mobile tools, and therefore I couldn't just disable that module.
The Fix
The fix I used was found here: http://drupal.org/node/770652#comment-4421310. By using drush with the -l flag and entering the full url, my drush began working correctly.
I believe what happens is that when drush loads the site, the mobile tools module tries to redirect the drush script to the mobile site. By using the -l flag, it prevented the redirect from happening.