Drush up burps whenever I subtheme without removing the project = "genesis" line in the subthemes info file.
The error is:
Error while trying to find the common path for enabled extensions of project genesis. [error]
The fix, suggested here for the fusion theme, seems to work with genesis as well: http://drupal.org/node/1043038 though I'm worried that this may break some linkage when it matters?