Tim Worstall writes about Teach First at the Adam Smith Institute Blog:

So we seem to have a situation where an absence of specific training in education produces better educators: or at the very least, ones that are no worse.

An excellent result I think all can agree: the policy implication is therefore clear, make teacher training a 5 or 6 week course, close the vast majority of the educating to educate system, save a great deal of money and possibly improve the education system, or at least leave it no worse.

Mark Wadsworth comments thus:

Having spent as many years in education as most people, it strikes me that teaching is largely an innate skill. Sure you need to understand the material, which is usually not that complicated, really. It’s getting the crowd on your side and motivating pupils that counts, skills which I doubt can be learned.

This I seriously doubt.  I certainly think that useful things about how to teach can be learned, if only by watching others do it in a way that you admire (currently my preferred method).

But what is surely true is that if the the choice is between very bad teacher training, of the sort that actually makes you worse than you would have been otherwise, and no teacher training, no teacher training wins.