I find it rather significant that the American Library Association published a whole issue entitled "Drupal in Libraries". While there are a couple other open source options in the library-sphere, Drupal is clearly gaining traction.
This (paid content) piece starts provocatively with a section entitled "Welcome to a new paradigm" and then jumps right into describing what Drupal provides to library scientists and how it can be used. The sections include:
1-Welcome to a New Paradigm
2-Getting Started With Drupal
3-Adding Stuff to a Drupal Site
4-User Management
5-Customizing the Drupal Look
6-Modules
7-The Trifecta
8-Other Modules of Note
9-Case Studies
10-Resources
I can think of a lost contract or two that probably would have been in-the-bag had this article/position been available to drive home the point that Drupal is a viable solution for libraries. It is one thing for a service provider to proposed their tool of choice, it is altogether another thing when one's professional association supports it.
Love live Drupal!