Don't take my word for it: listen to a beverage retailer.
Her complaints: producers without Web sites (I'd love to know which ones, since it seems like most wineries that you'll find in a store do have a Web site), sites without complete information, and sites which make it hard to find information (especially Flash-based sites).
Jeez, guys. These people are trying to sell your wines. Help them out for Pete's sake!
If you're in the retail side of things, agree or disagree in the comments!
See also: OwnIT: Your Wine, Your Way. I'm still thinking the OwnIT concept through, but it's certainly an attempt to address some of the issues that everyone faces when trying to get current, correct winery information.