I wonder where the different module versions are kept on a multisite installation.
Before I (re)discovered drush, I had several more sites sharing the core code and sites/all/modules a symlink to a common modules dir.
On upgrading core I set that link in the new sites/all dir.
And then I started using drush. So when I do drush up in the sites/my1stsite dir and it updates the modules, how can the other my2ndsite still have the old modules? (and be able to drush up-date itself?)