LINQ (.NET Language Integrated Query) will be very productive for developers and will add value to .NET applications.  It was heavily emphasized in one of the PDC keynotes which included Hejlsburg, Box, Anderson, and Guthrie.  See one of the accounts at TSS.  There is now a MSDN LINQ site and a site for development futures.

Consider this snippet in C# 3.0 that queries for a specific length, orders the result set, and returns in an enumerable reference:

class App
{
    static void Main() {
        String[] names = {“Burke”, “Connor”, “Frank”, “Everett”, “Albert”, “George”, “Harris”, David” };
        IEnumerable<string> expr = from s in names
            where s.Length == 5
            orderby s
            select s.ToUpper();
        foreach (string item in expr)
        {
            Console.WriteLine(item);
        }
    }
}