Help overcomng the empty nest syndrome?

Kids are grown and even though I'm leading a full busy life, I'm still missing motherhood. While they were growing up I was a very devoted mom and truly enjoyed the role. But now that they've got their own lives, etc., I feel left behind and discarded like a cheap raincoat. Is it normal to feel this way? How can I get past this so I can be happy for them instead of feeling unwanted?