Couple of pointless replies there seeing as the 747 and 737 both have winglets, the 747-400 having traditional types just like the A330/A340.
Boeing's new swept wingtip device is nothing to do with some silly cheerleading reason. They designed it to achieve everything a conventional winglet design does and more, at a lower drag penalty. It has more in common with something that took hundreds of millions of years to design, namely the wingtips of fast-flying birds such as hawks.
Modern materials also mean the devices can be implemented at a much lower weight than would have been the case if done in metals.