Expression Blend 4 launched with new features that are very mush interesting and simpler to use. So, here are some new features discussed in brief:

1. Make Layout Path: Path-based layout opens many interesting creative possibilities, way beyond just laying out things on a path. It is available in Objectà Pathà Make Layout Path.

2. Path ListBox Item: This option allows for more convenient and intuitive PathListBox creation. It is available in Assets library under the all controls option.

3. Property Changed Trigger: With the help of this new trigger an action can now be triggered when a property changes. You can find it under the head Common properties which is in properties pane.

4. Documentation and Search Links: This feature is simple but elegant. When you select a behavior then, at the bottom of the Properties panel links are displayed that lead directly to documentation or an online search that opens in your browser.