While the rest of us were unwrapping gift cards and gadgets last week, friends and family of James Cameron were getting an education. According to a publicist with the publisher Firefly Books, the Titanic director and deep-sea explorer gifted some 250 friends and family members a copy of Stephen Leahy’s “Your Water Footprint” for Christmas. The book, which details how much water is used in the production of everyday items, isn’t exactly cheerful—it requires 20 gallons of water to make one glass of beer. Gulp.—but it is nice to think that water conservation, which is so desperately needed here in Los Angeles, is on more minds now than it was on December 24. Beside, Oprah had Beats by Dre and initial stud earrings covered.