This sounds like pretty good news. Haven't had time to play with it, but looks significant. Deque (company behind it) is pretty much leader in the field.
from their email:
Deque has been invited to contribute the aXe open source library to the W3C WAI Evaluation and Repair Tools Working Group, as work is under consideration there for a normative set of rules for evaluating WCAG 2.0 conformance.