From Dan Fernandez

Expansions are fill-in-the-blank snippets of code that have several benefits.  They help automate boiler-plate code constructs like looping through a collection using a foreach statement, they help reduce syntax errors and they're a perfect example of code-focused RAD.  One of the things you'll notice with C# Whidbey is the concept of code-focused RAD, meaning RAD isn't just limited to drag-and-drop wizards, we're going to add productivity features directly into the code editor where C# developers spend the majority of their time.