What is it: Document Scanner is an app in the Android Market that allows you to "scan" a document, using your phone's camera, and convert it to a pdf. so that you can then email to everyone. A new feature is that you can now upload the document to Google Docs for storing.
How to integrate it into the classroom: There are an infinite number of possibilities for this app. Whether it's on a personal or educational level. Teachers can scan student projects to place in a student portfolio or to post on their blog. Students can scan notes from the teacher to reference information at a later time. And it can all be in one document instead of several images.
What makes this app stand out is that you can scan any number of pages and merge them into one document. You also have the ability to add scans to an existing pdf. and reorder the pages. The build in camera allows you to talk higher quality images.
I like to use it after meetings. I tend to take notes on post-its, napkins or whatever my pen will write on. This allows me to organize those notes to refer to later.