Developer[] developers = new Developer[] {
  new Developer { Name = "Paolo", Language = "C#" },
  new Developer { Name = "Marco", Language = "C#" },
  new Developer { Name = "Frank", Language = "VB.NET" },
};

var developersGroupedByLanguage =
  from d in developers
  group d by d.Language;

foreach (var group in developersGroupedByLanguage) {
  Console.WriteLine("Jazyk: {0}", group.Key);
  foreach (var item in group) {
    Console.WriteLine("\t{0}", item.Name);
  }
}
