
iPhone, iPad, and iPod touch Apps for (Special) Education" is a (PDF) list compiled & updated by Eric Sailers, based on an original list created by Samuel Sennott, Eric Sailers, & David Niemeijer.
Link to the most current version is available on Scribed.
For more great information, check out:
Eric Sailers' Speech-Language Pathology Sharing
Samuel Sennott's All Together We Can
David Niemeijer's Assistiveware (Mac-based accessibility & communication products)