This recommendation is for two books, both approaching the same topic from a slightly different vantage point: Geoff Colvin's Talent Is Overrated: What Really Separates World-Class Performers from Everybody Else and Daniel Coyle's The Talent Code: Greatness Isn't Born. It's Grown. Here's How.
Both deal with the modern science (neurological, psychological) behind how we develop skills (and the nature of world-class talent). Coyle speaks a lot about recent studies of the development of myelin in the brain and how that works in the development of skills: myelin is the substance that forms a sheath around nerves. In the case of disorders such as Multiple Sclerosis, myelin is destroyed and nerve impulses can no longer travel, leading eventually to total loss of muscular control (Jacqueline du Pre is the best known musician who suffered from MS). In the case of skill development, myelin in the brain is deposited around the incredible mass of interconnections in the brain and speeds up the electrical impulses as we repeat tasks over and over. This laying down of more myelin happens because of what scientist Anders Ericsson calls "deliberative practice" (both authors use his work extensively). This is a focused practice of tasks that are challenging, to the edge, but not beyond, what is possible to do (and, much like moving progressively heavier weights will cause or muscles to get stronger and bigger, causes myelin to be laid around nerve fibers with many layers, improving the conductivity of those nerves, and therefore the speed of impulses). Coyle calls this "deep practice" (a term I rather like). This is connected with other research that shows that extraordinary skill takes many hours (usually estimated at around 10,000 hours) to develop, but which only happens when the practice is of this nature (i.e., challenging, difficult). You can read Malcolm Gladwell's Outliers: The Story of Success for more about this. In a way, both authors take up Gladwell's style, which relies on many individual, anecdotal examples from different fields--and all three are superb writers.
Colvin's book was developed from an article he did for Fortune Magazine (he's a senior editor there), "What It Takes to Be Great," which you can find here.
I think both books are superb and have much to offer the musician, conductor, and teacher. Coyle speaks a lot about places where extraordinary numbers of talented people originate (and more importantly, why): soccer players in Brazil, KIPP (Knowledge is Power Program) schools, South Korean female golfers, etc. He also looks at teachers and coaches who have had special success, from John Wooden (former UCLA basketball coach) to Linda Septien of Dallas, who's had extraordinary success teaching/coaching pop singers.
These books offer a glance into the world of "genius," which science is now showing is much less of an inborn/genetic thing, and capable of being developed more than we've ever thought before. They're also a guide to developing your own, or others', talent. As with Carol Dweck's Mindset: The New Psychology of Success (written about in an earlier post here), they're well written and, in fact, "easy reads," although both will repay repeated readings and study to translate into just how you will adapt this information to yourself, your students, your teaching, and your choirs.