We have the know-how to make the web more accessible; what we're lacking is the will to act on it. The a11y bugs project is a new grass roots effort that aims to spur the stakeholders in web technology into action, to make the web more usable for everyone.
Consistent implementation across browsers is probably the single most important factor for success of any given web feature. We've seen this with CSS, which was mostly unused because the leading browsers had different implementations. In large part thanks to an advocacy effort from WaSP, browser vendors started to harmonize CSS implementations and CSS became the norm.