One more point, while it is true that formal teaching experience doesn't matter when making a faculty hire at a research university, evidence of strong teaching skills does. For example, the quality of the research seminar and one on one interactions with faculty is used as a predicter of teaching suceess. And, its not that teaching ability isn't important, its that its an expectation rather than a discriminator. Since there is more variation in research ability, that is selected for first, if you don't have a strong research record you will be less competitive, but amongst the group of candidates with strong research records, the ability to teach well will also be expected, and considered strongly. Its just that practical training as a teacher takes place after practical training as a researcher (with the exception of all the skills that one aquires from presenting and defending ones work along the way). We generally let our junior faculty ease into their teaching assignments (as they also start to develop their research programs) with a lot of guidance as needed.