Is there a built-in way to use proptypes to ensure that an array of objects being passed to a component is actually an array of objects of a specific shape?
Maybe so
And there it is... right under my nose:
From the react docs themselves: https://facebook.github.io/react/docs/reusable-components.html
// An array of a certain type optionalArrayOf: React.PropTypes.arrayOf(React.PropTypes.number),