Microsoft weren’t happy with just adding LINQ into C# 3.0, which by itself is an amazing feature, so they added a whole load of other useful stuff. Half of them are just syntactic-sugar but you can see how they’re going to save you time when coding. The other half let you do some cool tricks with very little effort.
Here’s a link to a MSDN Chopsticks webcast on C# 3.0 Language Enhancements, but you’ll need a Windows Live ID to get in.