The Dart Editor and SDK was updated to version 0.7.3.1_r27487 with the Performance and Analysis fixes. Also the Dart Editor was given a TODO comment feature. Interestingly the option to create a new Web_UI project has been removed.
Recently Google pushed Chrome desktop apps and one of the Dart Editor team members is working on a Chrome App called Drake. Drake describes itself as 'A Chrome app based web development environment' and is written in Dart. I will trying this out very soon!
Seth Ladd has updated his Polymer.dart samples "Auto-complete, GWT Contacts example, and polymer-element-ification for the Polymer.dart mini-samples.". These samples have proved invaluable for most of my Polymer experiments. Also don't miss his up to date presentation on Dart from the JavaZone conference.
Chris Strom shared a blog post regarding unit testing of a Dart canvas application.
Staying with HTML5, dart-webgl a re-write of learningwebgl.com lessons to Dart. Take the web into the third dimension! I can see Teapots in front of my eyes already...