So by accident I came upon what looks like LITA's official page for the Drupal4Lib Interest Group. Apparently how the group got started is a mystery to LITA since all they have under 'Origin' is this:
To contribute information about the history of this interest group, contact LITA's Web Coordinating Committee at email@example.com.
Now that's kind of strange! I mean all you have to do is go to LITA's own blog and there you'll find the following contemporary account:
Drupal4Lib BoF at ALA Anaheim [6/30/08]: First up on the agenda was setting up the Drupal IG, making sure we have enough signatures and asking for volunteers to serve as Chair and Co-Chair. For the first year, Leo Klein (i.e. me) graciously volunteered to serve as chair and Ian Chan as co-chair.
The name for the IG is 'Drupal4Lib' and our purpose is “to promote the use and understanding of the content management system, Drupal, by libraries and librarians”.
Well, at least they got the name of the IG right.
UPDATE (6/18/12): Well, that's nice. The LITA people added the following note as to the origin of the Drupal4Lib Interest Group:
The LITA Drupal4Lib Interest Group was formed during the 2008 ALA Annual Conference at a Drupal BoF (Birds of a Feather) meeting. The informal gathering consisted of about 20 librarians with varying experience with content management systems. Some participants attended the BoF to research content management systems, others came demonstrate their Drupal-powered library sites or personal projects. During the meeting, attendees collected signatures to set up the Drupal interest group. Leo Klein and Ian Chan volunteered to serve as co-chairs. The name ‘Drupal4Lib’ was choosen and the attendees decided the purpose of the group was, “to promote the use and understanding of the content management system, Drupal, by libraries and librarians.” During that conference, LITA also hosted the Pre-Conference, "Getting Started With Drupal."