This week in Dart, the Dart Editor/SDK was updated to build 25017. Thanks to the Dart team for all their hard work.
Developers have not been slow to get started on polymer.dart (the successor to WebUI). There's some useful notes on converting existing WebUI apps that could save you a lot of time!
Finally, for a different Dart weekly update, try the excellent Dart Weekly email newsletter which also has good coverage of the updates of the community Dart packages.