I use microdata (http://schema.org/Book) for a blog (wordpress). And it causes problems with the sharing tool of Twitter.
And to call the twitter sharing tool :
You can see the problem here : http://www.du9.org/chronique/lou-t-6-lage-de-cristal/
or here : http://oi44.tinypic.com/mlqvzc.jpg
If someone have an idea to resolve this problem, don’t hesitate