That'd be the 'Web Content Accessibility Guidelines 2.0' – a 'wide range of recommendations for making Web content more accessible' with success criteria 'written as testable statements that are not technology-specific' (i.e. possibly including JavaScript or Flash as well as HTML and CSS, but the criteria are still sorted into A, AA and AAA).
Putting that in context, a blog post on webstandards.org, 'WCAG 2 and mobileOK Basic Tests specs are proposed recommendations', says:
It's possible that WCAG 2 could be the new accessibility standard by Christmas. What does that mean for you? The answer: it depends. If your approach to accessibility has been one of guidelines and ticking against checkpoints, you'll need some reworking your test plans as the priorities, checkpoints and surrounding structures have changed from WCAG 1. But if your site was developed with an eye to real accessibility for real people rather than as a compliance issue, you should find that there is little difference.
How to Meet WCAG 2.0 (currently a draft) provides a 'customizable quick reference to Web Content Accessibility Guidelines 2.0 requirements (success criteria) and techniques', and there are useful guidelines on Accessible Forms using WCAG 2.0, with practical advice on e.g., associating labels with form inputs. More resources are listed at WCAG 2.0 resources.
I'm impressed with the range and quality of documentation – they are working hard to make it easy to produce accessible sites.