This is a great article from UX Magazine. It does a great job defining interactivity and gives video examples of eBooks and eBook apps that have value.
PE teachers are often left out when it comes to technology integration. This is a great article full of suggested apps and links for integrating an iPad into a PE curriculum.
This is a great blog from a group of educators in Texas. They have written a few good articles about iPad deployment as well as mobile technologies in the classroom.
We use VoiceThread in a lot of our EdTechTeacher workshops as it is completely web based and now includes an iPad app. As a tool, it can create digital stories, be used for foreign language exercises, or support the creation of collaborative study aids. This library is a database of articles about successful VoiceThread projects.