HTML5 is a new version of HTML and XHTML. The HTML5 draft specification defines a single language that can be written in HTML and XML. It attempts to solve issues found in previous iterations of HTML and addresses the needs of Web Applications, an area previously not adequately covered by HTML.

To get a really good idea of how HTML5 is changing the web. This is a great collection of sites that are currently coded in HTML5. You will find alot of new stuff to play around.

1) Klix

2) Trefl

3) The Salad Bar

4) Safari 5

5) ANDRAS LENGYEL

6) Talita pagani

7) Emmanuel Pelletier

WooConcept

9) Nick cates Design

10)spaghetti*

11) Diablo

12) Rastro

13) Mip Design Themes

15) MRM Worldwide

16) Deaf Pigeon

17) Asriel

18) Central Mass ChemDry

19) Créart Magazine

20) Waterford Family Bowl

21) Inej Autocentar

22) Design & Stone

23) Rider

24) Blog Maison Écologique

25) Studio 78

26) Municipalité de Saint-Isidore

27) Friendsof42

28) Marc Watts

29) Constantia Strasbourg Neudorf

30) Globatec

Another best html5 resources site here http://www.html5beauty.com