Everyone who got free shipping on orders over $50 (or less, even) please use it so the results of their marketing will show that to be a good threshold and they will then offer it on a regular basis
My threshold was a little higher, but buying anything during this "test" should help Lego realize that free shipping is an incentive to buy straight from the source. I just bought the Winter Cottage with my VIP points and got the Monster Fighters poly with free shipping. If I had waited until October first to order, the points I earned would have negated the shipping.
All in all, I hope I've helped somewhat in the "Free Shipping" from Lego department. Just had a lot of little things kicking around in my cart, then came the cottage...