A couple of years ago, Sierra Nevada Brewing paired up with Dogfish Head and created 2 beers, Life & Limb & Limb & Life. Life & Limb found bottles and draft handles around the country. At the time, it seemed like the beer was a one time brew. Not anymore! It’s currently being brewed as we speak.
The collaboration touted some unique ingredients: Estate barley from Sierra Nevada brewery in Chico, California. Pure maple syrup from the Calagione farm in Massachusetts. Also, for the first time in craft beer, birch syrup from Alaska used for natural carbonation. Yeast strains from both brew houses were combined to make a unique signature.
More info on the original collaboration at Life-limb.com. The website hasn’t been updated since the original release as far as dates are concerned.