This is one of the neatest examples of language evolution that I have seen. There are a few excellent academic treatments of the subject available, one being here. http://www.worldwidewords.org/qa/qa-hom1.htm
I had never heard the expression "hone in on" until the past two years, and have heard it used (so far) only by under thirties, who have never heard of a radio homing beacon. To them, homing in made no sense. Unlike the dumbed-down use of unique, which has destroyed the value of a word that was "unique" in it's meaning (or, perhaps, singular), the morphing of home to hone, while almost certainly coming about through misunderstanding, has some logic behind it. There is no harm here, only a little confusion and fun discussion, until home in is finally vanquished in the USA. From there, who kows where it will go, but my vote is that it will prevail throughout the English speaking world.