Google has been uploading tons of videos of sessions from Google I/O, and these two deal specifically with the Dart programming language, so if you're looking to learn more about it, and were unable to attend the event, you're in luck.
The first video is from the session: Dart - A Modern Web Language. Here's the video's description:
The two creators of Dart will discuss the rationale behind Dart's design and its impact on web scalability and performance. They'll also present how Dart helps developers innovate by increasing their productivity without breaking backwards compatibility.
The second is from the session: Migrating Code from GWT to Dart. Here's the description:
According to Google, you should learn Dart because: