Are Multiple drupal core updates possible through Drush? Drupal 7.15 to7.16

Currently, using 7.15 and need to update over 20 sites with Drupal 7.16. I have root access to dedicated server.
Has anyone created a document or drush to do this without updating each site individually?

I may have missed discussions on this over the past few months. Just a few links wil be fine.

Thanks