If you're spreading the word about firefox by wearing your t-shirt out in the streets, hanging posters at your office, handing out flyers or CDs on your campus, displaying a bumper or window sticker on your car, or other creative marketing efforts then get a photo of it and join our Around the World in Seven Days campaing over at SpreadFirefox.com.
update: a screenshot of your desktop is not a photograph of firefox in the wild.
update2: and neither is a webcam shot of you sitting in front of your PC with a Firefox wallpaper.
