A local brewpub describes one of its current beers as a "dry porter". I got something else instead, so I didn't taste it. I'm familiar with both porters and stouts (and the controversies over what the difference is), but what's a dry porter? I found a non-local example and a recipe, but neither describes the results enough for me to be able to tell what's "dry" about either.
As @Eric mentioned in the comments, it is similar to wine, where you would expect a dry (or brut for sparkling) wine to have low to no residual sugars. A dry beer (porter, in this case) is brewed specifically to ensure that the carbohydrates are all converted to fermentable sugars, which are then fermented as the term would indicate, leaving you with a higher alcohol beer with less residual sugar than an a traditional fermentation.