About.com has a nice piece from Sue Watson on how to design differentiated assessments for the inclusive classroom. Watson explains the purpose of assessment and its role in lesson design. She also explores methods for differentiation (e.g., graphic organizers, presentations, informational brochure) and ideas for assessing beyond the standards. Teachers might, for instance, need/want to assess communication skills, participation, and listening.
This article is short, filled with examples (and a few links to resources) and potentially very helpful to those wanting more information on this topic.