I have never been one to force my children on the issue of weaning. Zosia weaned herself-- looked up into my eyes, shook her head and said "All done." when I offered her milk. She was about a year old. Lily, on the other hand, has been a more steadfast nurser. She has often asked to nurse in the middle of the day, noisily objecting when I am not present at bedtime. So I just haven't pushed the matter, and have nursed her longer, enjoying the extra snuggle time built into our day.
Recently, Lily has been forging into independence in many ways: insisting that she does things all by her self, even when the task seems too big, shutting the door to Zosia's room when she and Zosia are playing, asking to actually walk when we're going on walks... and no hand-holding, please. So I guess it doesn't surprise me that Lily has just as naturally moved towards weaning. First, accepting a cup of milk at naptime in lieu of nursing. Then, magically, accepting a cup of milk at bedtime last night. No tears, nothing. Just acting like "Oh, this is how we've always done it."
Eighteen months to the day, and moving forward into the world independently.