Fi Share card is smart: each time you bring your camera home to your wireless network, it transmits your photos back to the computer, automatically and wirelessly. It can also upload them to Flickr, Picasa or another online photo-gallery site, automatically and wirelessly. Here's how: The 2-gigabyte memory card is compatible with most digital cameras has Wi-Fi networking built in. The Eye-Fi Explore card, meanwhile, has an even more amazing trick up its sleeve: it invisibly stamps every photo with where you took it. Once on your Mac or PC, each such photo shows the city and state where it was taken. You can also click to view either a street-map view or an aerial photo, clearly showing where you were standing when you pressed the shutter button. The card does this through a new technology, a rival to G.P.S., called W.P.S.—Wi-Fi Positioning System. A company called Skyhook came up with it. (Skyhook's first well-known client was Apple. The original iPhone doesn't have actual G.P.S., but it does have Skyhook's “locate me” feature.) Understanding how Skyhook works is fascinating, writes David Pogue in the New York Times. At this moment, more than 70 million Wi-Fi base stations are sitting in homes, offices and shops. Each broadcasts its own name and unique network address (called its MAC address — nothing to do with Mac computers) once a second. Skyhook has managed to correlate those beacon signals with their physical locations and now its database knows about 50 million hot spots – and the precise longitude and latitude of each. But that's also Skyhook's biggest weakness is coverage. The 50 million hot spots it knows, the company says, is enough to cover 70 percent of the populated areas in the United States and Canada, and 50 percent of Europe. But that means that the Eye-Fi card draws a blank in some of the situations when you'd most want a location fix for your photos: hiking, skiing, camping, boating or traveling abroad. These are places where you're not likely to find any Wi-Fi signals at all. – Extracted from the State of the Art in The New York Times. __
