First thing I found was a New York Times Magazine article titled "Dropping Acid", which caught my attention and provides a nice history of this ancient beverage. Also included was a basic recipe for any kind of fruit shrub.
Turns out that the real connoisseurs of shrub recipes are the "cocktail geeks" and I came across an interesting and funny article called Cocktail 101: How to Make Shrub Syrups. This also included a recipe as well as links to other resources.
I had no idea that shrubs were that popular, nor versatile. But what fun we will have experimenting with this one!