An additional extension method for attempting to get the Guid out of a claims identity object

IIdentityExt.cs

using System;
using System.Security.Principal;

namespace Microsoft.AspNet.Identity {

	public static class IIdentityExt {

		public static Guid GetGuid(this IIdentity identity) {

			var result = Guid.Empty;

			string id = identity.GetUserId();

			Guid.TryParse(id, out result);

			return result;
		}
	}
}