Wednesday 27th June 2012 you can watch it live at Google IO.
I attached the official post on DART discuss.
Hello fellow Dartisans!
Lars Bak and Kasper Lund will present “Dart: A modern web language” at Google IO, and you can watch it LIVE! Tune in to https://developers.google.com/events/io/ on Wednesday, July 27th at 1:30PM (US/Pacific) to watch the live broadcast.
If you can’t make it, no worries, this and other Google IO presentations will be recorded and uploaded to YouTube after the show.
Thanks for all your support,