'drush mm list' sees no installed modules, only 'available modules'

With the HEAD version of Drush and drush_mm-6.x-2.x-dev-2009-Mar-23 (latest), 'drush mm list' sees all modules in sites/all/modules as available but not installed (error). So no enabled modules are listed.
This is with a multisite setup, so I actually used 'drush -l mysite.local mm list'. In fact almost all modules in the folder are installed in my Drupal installation.

I don't know if this is because of drush_mm or drush core. The same Drupal installation with the deprecated drush and drush_mm versions does list the modules correctly.