I came across a January post from David Smith at Revolution Analytics, in his Revolutions blog. It's titled, An Introduction to Applied Econometrics With R, and it refers to a very useful resource that's been put together by Bruno Rodrigues of the University of Strasbourg. It's called Introduction to Programming Econometrics With R, and you can download it from here.
Bruno's material is a work in progress, but it's definitely worth checking out if you're looking for something to help economics students learn about R in an introductory statistics/econometrics course.