.NET Enumeration allows comma in the last field

It has no special meaning, just the way the compiler works, it's mainly for this reason:

[FlagsAttribute]
public enum DependencyPropertyOptions : byte
{
           Default = 1,
           ReadOnly = 2,
           Optional = 4,
           DelegateProperty = 32,
           Metadata = 8,
           NonSerialized = 16,
           //EnumPropertyIWantToCommentOutEasily = 32
}

By comment request: This info comes straight out of the C# Specification (Page 355/Section 17.7)

Like Standard C++, C# allows a trailing comma at the end of an array-initializer. This syntax provides flexibility in adding or deleting members from such a list, and simplifies machine generation of such lists.

Also (to Nick Craver post) its much easier to add new enumerations.

This behaviour appropriate not uniquely to enums. Consider following:

var list = new int[] { 1, 2, 3, };

One other reason: It makes it easier to code gen.