I have a bush in my back yard, and have also encountered a similar VERY large bush while walking my dog. The berries look for all the world like what we called "wacholder" in Switzerland, perhaps even "Weintrauben." The berries are small, maybe 1/2" in diameter and grow in large clusters with reddish stems connecting to the main shrub. The actual clusters of berries are more or less flat. The leaves are simple oblongs in shape. I know we made jam out of something very similar in Switzerland while I lived there years ago, but have no memory of the appearance of the shrub. I don't want to harvest these berries to make jelly and end up discovering that they are poisonous.