By Evan Dawson, Managing Editor For our next guest commentary in this series, we wanted to turn to the retail side of wine. Daniel Posner is very well known in the world of high-end wine and online wine discussion. He's not afraid to speak forcefully — and occasionally controversially. He's the owner of Grapes The Wine Company in White Plains, New York and his daily wine deal email is a popular list to be on. And, he runs WineTalk.com, a growing discussion board that focuses on wine in all of its forms. And you'll see, Daniel carries some New York…