In a steel bowl add the egg yolks, sugar, and coffee and whisk over a pot of boiling water, the bottom of the bowl not touching the water. Whisk the mixture until well blended and creamy. If the temperature becomes too hot, remove the mixing bowl from the boiling water. You do not want to cook the eggs you just want them to be silky, creamy, and frothy. Divide the berries among 4 glasses or serving bowls and drizzle the zabaglione over the fresh berries.