I just presented my C#3.0 session at TechEd Orlando titled "DEV346 - Microsoft Visual C# Under the Covers: An In-Depth Look at C# 3.0".  The talk introduces the new C# language features and takes a tour behind the scenes of LINQ to Objects to see how C# is used to enable creating rich new kinds of APIs.

Here are the code samples from the talk:

FirstDemo.cs     SecondDemo.cs

And here's a little in-line snippet - the results of the first demo:

using System;
using System.Collections.Generic;
using System.Linq;

class Customer
{
    // C#3.0 Feature:  Auto-Implemented Properties
    public string CustomerID { get; set; }
    public string ContactName { get; set; }
    public string City { get; set; }
}

class Program
{
    static void Main(string[] args)
    {
        List<Customer> customers = LoadCustomers();
        
        // C#3.0 Feature:  Query Expressions
        var query = from c in customers
                         where c.City == "London"
                         orderby c.ContactName.Split(' ')[1]
                         select new { c.CustomerID, c.ContactName };

        foreach (var item in query)
            Console.WriteLine("{0}, {1}", item.CustomerID, item.ContactName);
    }

    private static List<Customer> LoadCustomers()
    {
        // C#3.0 Feature:  'var' - Local Variable Type Inference
        // C#3.0 Feature:  Collection Initializers
        var customers = new List<Customer>()
        {
            // C#3.0 Feature:  Object Initializers
            new Customer { CustomerID = "ALFKI",
                                   ContactName = "Maria Anders",
                                   City = "Berlin"},
            new Customer { CustomerID = "ANATR",
                                   ContactName = "Ana Trujillo",
                                   City = "M?xico D.F."},
            // more customers ...
            new Customer { CustomerID = "WOLZA",
                                   ContactName = "Zbyszek Piestrzeniewicz",
                                   City = "Warszawa"}
        };

        return customers;
    }
}