Re http://twitter.com/#!/jonskeet/status/21507535424983040

SkipWhile.cs

private static IEnumerable<TSource> SkipWhileImpl<TSource>(
	IEnumerable<TSource> source,
	Func<TSource, bool> predicate)
{
	using (IEnumerator<TSource> iterator = source.GetEnumerator())
	{
		do
		{
			if (!iterator.MoveNext())
				yield break;
		} while (predicate(iterator.Current));
		
		do
		{
			yield return iterator.Current;
		} while (iterator.MoveNext());
	}
}

SkipWhileIndex.cs

private static IEnumerable<TSource> SkipWhileImpl<TSource>(
	IEnumerable<TSource> source,
	Func<TSource, int, bool> predicate)
{
	using (IEnumerator<TSource> iterator = source.GetEnumerator())
	{
		int index = 0;
		do
		{
			if (!iterator.MoveNext())
				yield break;
		} while (predicate(iterator.Current, index++));
		
		do
		{
			yield return iterator.Current;
		} while (iterator.MoveNext());
	}
}