Alder Yarrow at Vinography has this to say about winery Web sites:
I'm happy to say that at least all the wineries had web sites (which wasn't true until just a couple of years ago). But many of the sites were out of date (meaning they didn't actually list the winery's current releases); a few failed to list phone numbers or e-mail addresses; and probably close to 50% of the wineries that offered public tasting rooms hadn't bothered to place themselves in Google Maps so that customers could easily find them.
(from his post, How Wineries Will Fail in the 21st Century).
Current releases? Given the the fact that you only release wines a few times a year, it should be a "release checklist" item. Phone Number? Readers of this blog know that your winery phone number should be in the header of every page on your site (in subtle, but obvious fasion). E-mail? Not as important as your phone number, so put it on the Contact Us page. Map? It's a given for *any* retail Web site (e.g. a winery with a tasting room).
(If you have a moment, please take my 2010 Winery Sales Survey, and pass the link along to any other wineries you know. Thank you.)