Gregory is a freelance writer and author based in San Francisco who writes about travel, food, and the natural world.

His first book, The Coffee Book: Anatomy of an Industry from Crop to the Last Drop, (co-authored with Nina Luttinger) was published in 1999 by The New Press. The Coffee Book was well-received by both the coffee industry and the reading public, and garnered numerous excellent reviews from such voices as the Economist magazine, the Chicago Tribune, LA Times, New York Newsday, Toronto Globe and Mail, Baltimore Sun, and the New York Times, which excerpted the book. The Coffee Book is now in its fourth printing, and has been translated into Swedish. A second edition that will also be published in Japanese and Spanish is scheduled for 2006.

Window Seat: Reading the Landscape from the Air was published by Chronicle Books in 2004. The book went into its fourth printing and sold 20,000 copies within six months of publication. It was featured on NPR's All Things Considered, reviewed by the Wall Street Journal, the Chicago Tribune, the National Post of Canada, Knight-Ridder, and in the New York Times Review of Books. Window Seat was also featured in Travel + Leisure, Men's Journal, and numerous in-flight magazines. A followup title, Window Seat Europe, was published in 2006.

Gregory has written for numerous publications including the New York Times, Harper's Magazine, Salon, The Economist, Travel + Leisure, Decanter, HotWired, New York Magazine, Mother Jones, Gastronomica, and others. He is a contributing editor at Other Magazine and has contributed a biweekly column for SFGate, the online edition of the San Francisco Chronicle.