At Hypertext '04, I spent a delightful day touring Napa with Hugh Davis, who knows more than somewhat about wine. Hugh had brought a handy little bookshelf of well-written wine books for plane reading; as soon as I got home, I sent off for a copy of each.
Jancis Robinson's How To Taste suggests that the best way to learn what's what is simply to compare. If you open two or three bottles at once, taste each, and enjoy them all for a few days, she suggests you'll learn a lot more than by tasting one at a time. Unlike lots of wine writing, Robinson's prose is clean and sensible, and the book is filled with fun and tasty exercises.
In The New Yorker, Gopnick has a gem of a review, occassioned by William Echikson's Noble Rot. Interestingly, Calvin Trillin has a long New Yorker piece on wine as well, to which Gopnick alludes. This gives us a wonderful opportunity to compare Gopnick and Trillin at the same table.