The main examples right now are from a Google tech talk showing some HTML5 demos written on the fly. Some of the demos, as well as the video from the talk, are available online.
These demos were created to show some of the features of Web Forms 2. Not all these features were kept, but the demos remain for those looking at the history of HTML5.
datetime
input type of Web Forms 2.0form
attribute in Web Forms 2.0