MangoMon is a commerical organisation providing online tools for special needs students. They also have some good ideas on teaching and learning uses of online tools and technologies. For uses of iPods and iPads in classroom see this article. An interesting video on this page shows hearing impaired students learning via the use of an iPad. Scroll halfway down to see video.
Spectronics, another special education supplier also provides some good links to the use of iPads in education in their article "Educational Apps and resources for the iPad and iPhone".
CEO Parramatta also provides links to the use of Ipads in Special Education via the Learning and Teaching with Ipads blogspot. See the Special Needs Uses tab.