I've been meaning to do this ever since we completed all the site evaluations for The Winery Web Site Report:
The list is pretty short, which is unfortunate, since blogs are a great low-effort way to involve your customers with your winery. According to our database, a fraction of a percent of wineries with Web sites have blogs.
If you are aware of any other winery blogs, please let me know so I can add them to the list!
(and that's the answer to Tom's question)