
Matt Leacock, Erin Malone, Chanel Wheeler wrote a paper about the Yahoo Pattern Library and its implementation:
Yahoo’s multiple business units, each containing decentralized user experience teams, have a natural tendency to design different solutions to similar problems. Left unchecked, these differences would weaken the Yahoo! brand and produce a less usable network of products. Designers and managers have discussed “standards” as a way to solve this problem but this standards content (often contained only in the memories of designers) has never existed in a commonly accessible format. (…)
The pattern library allowed our small, centralized group to tap into the broad expertise of the Yahoo! design staff. What would have been impossible to write (authoritatively) by a small team is now being contributed to and reviewed by an expert staff. We were able to achieve this by understanding and agreeing on the problem, building a workflow that fit with the existing design process, generating buy-in by creating incentives for contributors, and by carefully designing and building an application with attention to user feedback.
related links
Full Paper: Implementing a Pattern Library in the Real World