Visitors to your Web site are unescorted. Unless you're obsessively monitoring your site in real time, you probably don't even know they're there. But they are out there talking about your wines and your winery, based on what they experience on your Web site.
For example, check out this post, Stormhoek marketing wine one blogger at a time, by Robert Scoble of Microsoft. Read the comments as well. Bonny Doon and their wines come off very well, even though the ostensible reason for the post is Stormhoek, a South African winery not even distributed in the US (yet) which is courting of bloggers and gaining some visibility as a result.
Bonny Doon probably didn't know that they got visited by one of the most popular bloggers on the Internet (and probably some other people as a result). Your site needs to be ready to serve visitors (and leave them with a positive impression) at any moment. There's no chance to put your best foot forward unless it's already sticking out there. It's like having an unescorted visitor walk into your winery. What impression are they going to walk away with?
(By the way, Robert's post is presently the #2 result if you use blogsearch.google.com to search for Bonny Doon)