Here's a well-written story about how librarians have undertaken a major open source project with great success:
The system, Evergreen, whose 1.0 release came in November, is an Integrated Library System (ILS): the software that manages, catalogs, and tracks the circulation of library holdings. It's written in C, JavaScript and Perl, is GPLed, runs on Linux with Apache, uses a PostgreSQL database, Jabber for messaging and XUL as client-side software. The system allows easy clustering and is based entirely on open protocols.