The W3C is (probably) launching a new working group to develop a “Timed Text” specification. Although membership in the working group itself is limited to W3C members and invited experts, they’ve submitted a draft charter to the Timed Text mailing list, and they’re looking for your feedback. (For example, is two years a realistic schedule for the process, or too long?)
The mission of the Timed Text Working Group (TTWG) is to develop an XML-based format for time-based text, like RealNetworks’ RealText, albeit better and sans “Real-isms”. This Timed Text format could be used in SMIL, as a standard interchange format, etc. (Thanks, Philipp!)