There are a number of test implementations in progress, based on the V.6 specification submitted to schema.org. As these become publicly available, they will be listed here. We’ll keep you posted, so subscribe to the update email or our blog.
Bookshare Over 197,000 titles are available in Daisy, BRF and audio formats. This is tagged with Accessibility Metadata and LRMI tags. There is an example of this on the live examples page, from early in the project. Current examples are CK-12 Geometry at Bookshare’s catalog and the structured data testing tool. There is also a blog that describes the launch of this service and some of its attributes.