The goal of using a Wiki is simple: keep artifacts current through collaborative ownership.
The multitude of successful open source projects using a Wiki based approach is the best justification why a community based approach works. Additionally, a perspective from academia centric sources, with associated analysis, will help you build a business case.
If you're considering pursuing a Wiki based approach consider the following resources:
- Experience Using the Web-Based Tool Wiki for Architecture Documentation (thorough and free report based on actual project experiences - SEI). Blurb.
- On-line collaborative software development via wiki (from Proceedings of the 2007 international symposium on Wikis - ACM)
- Using Wikis in Software Development (IEEE Software)