What are some of the new features that can be used in .NET 2.0 that are specific to C# 3.0/3.5 after upgrading to Visual Studio 2008? Also, what are some of the features tha
You can use any new C# 3.0 feature that is handled by the compiler by emitting 2.0-compatible IL and doesn't reference any of the new 3.5 assemblies:
Func<..>
, not Expression>
)System.Runtime.CompilerServices.ExtensionAttribute
)IEnumerable
extension methods, see LinqBridge)