From the DITA 101 page on dita.xml.org, one of the best DITA resources on the Web:
The DITA OASIS Standard defines an XML architecture for designing, writing, managing, and publishing technical documentation in print and on the Web. DITA (commonly pronounced dit'-uh) builds content reuse into the authoring process for document creation and management....Focusing on a common topic model as a conceptual unit of authoring, DITA provides a core set of topic types derived from concept, task, and reference...DITA enables organizations to deliver content as closely as possible to the point-of-use, making it ideal for applications such as integrated help systems, Web sites, and how-to instruction pages.
So, why does this matter to content creators? For a number of reasons, not the least of which are that implementing DITA can save you time and a lot of money.
There was a terrific DITA case study posted on the Data Conversion Laboratory site recently. Titled How our DITA Conversion Saved us 100 Grand, for Starters, the piece focuses on a regulated medical device company that was tasked with implementing a multilanguage content management system.
Needless to say -- it is a case study, after all -- the project was a success. There's a lot of helpful detail on the process from start to finish, and while it may not apply directly to your organization's needs, there is a lot to be learned here. It's certainly worth a read for anyone considering migrating to a DITA-compliant, XML-based platform.
Tip of the hat to The Content Wrangler, where I first saw a link to this piece.