Shell is filling cable channels with commercials for GTL, or gas-to-liquids, and someone asked me about it, so here's your answer:
GTL is a type of liquid fuel produced from natural gas. It isn't classic liquefied natural gas, which is natural gas cooled to the point where it turns into a fluid. Instead, methane from underground is cracked by catalysts and heat, turned into synthetic gases, and then transformed into a liquid similar to diesel. The process resembles the coal-to-liquid Fischer-Tropsch process devised in the 1920s.
Shell already makes token amounts of GTL in a plant in Indonesia; much of that fuel gets mixed into the diesel Shell sells in Europe. The next big step comes when the company opens the Pearl facility in Qatar in 2010. (Shell showed us the first fully GTL car at a conference in Qatar in late 2005.) That plant will produce 140,000 barrels of GTL and 120,000 barrels of other byproducts daily. While tiny from a global perspective, that much fuel can keep a lot of cabs on the road.
While GTL results in fewer greenhouse gases than conventional diesel, it ain't cheap. Shell, in fact, is getting its natural gas to make GTL in an area where it's impractical to build pipelines for selling regular natural gas. GTL will be sold into megacities in the emerging world like New Delhi that are struggling to contain emissions.
Oh, and you can drink it. It doesn't taste great, but you won't end up in the hospital. Biodiesel is drinkable, too.