According to this website: https://www.w3.org/WAI/WCAG20/from10/diff.php, WCAG 2.0 differs from 1.0 primarily in how each acceptance criteria is explained when a test fails to meet a criteria (in WCAG 2.0 is much more granular/specific than 1.0), and I quote: "The fundamental issues of Web accessibility are the same, though there are some differences in the organization and requirements between WCAG 1.0 and WCAG 2.0."
So for Web, as long as the system enforces WCAG at a given priority level, it seems to be irrelevant whether it's WCAG 1.0 or WCAG 2.0 because the version differences are in the way issues are organized when reported, not enforced by the system (and Tridion is not a WCAG testing system). So for RTFs, Tridion will give you WCAG HTML produced by the WYSIWYG; while anything on Content Delivery is your custom front-end code, which is outside of Tridion's enforcement jurisdiction.