Via the hardwork of WHATWG and the W3C, a second Working Draft is now available for HTML 5. The W3C consider a Working Drafts ready for review by the community and feedback is always welcome via public-html-comments@w3.org
There’s a number of ways to view changes between the current and previous draft:
Anne van Kesteren’s HTML 5 differences from HTML 4, includes this section helpful section: HTML 5 Changelog
Michael Smith’s HTML 5 publication notes includes provides “supplmemental information” mostly relating to the differences between the previous and current drafts.
If you’d like view every little change, you can also view the HTML marked-up (including color highlighted) diff version of the HTML 5 specification.