Google released a short PDF all about accessibility of Google Apps. The Administrator Guide to Accessibility (link opens a PDF) is a twenty-one page guide to accessibility settings in Google Apps. The guide covers accessibility settings for Gmail, Calendar, Drive, Docs, and Presentations. The guide also covers apps that are not fully accessible yet including some features of Sites, Chat, and Groups.
Applications for Education
If you're a Google Apps administrator in your school, this guide is for you. If your school uses Google Apps for Education and you work with students who use assistive technology, this guide could be a handy resource for you too.