Google has launched a new website aimed towards condensing all of their accessibility-related resources and news in one place. Right now the hearing-related accessibility is mainly in captions on Google Video and YouTube, but accessibility is a constantly evolving thing, and what's there now could be greatly enhanced in the future, plus it looks as though they have some great resources and features for those with other disabilities, especially visual.
In their blog post about the new site, they also mention an open-source framework called AxsJAX, which can help developers bring everyone up to the same experience, regardless of the adaptive technology they may be using. I had never heard of AxsJAX and I think it's pretty cool.
Google is asking for feedback - might be a good way to get your ideas about accessibility out there and implemented.