It's still about ten years or so away from becoming a reality, but National Geographic has an article about one zoologist's quest to build a Gattaca-style handheld DNA scanner that would be able to quickly and easily identify the species of any plant or animal. The scanner analyzes DNA bar codes, which are basically species-specifc sequences found in a single gene known as CO1 which just happens be common to all plants and animals (though CO1 doesn't work quite as well for differentiating plant species). Researchers are building a database of DNA bar codes right now, and have so far catalogued about 2 million of the ten million species of plants and animals that are estimated to live on earth. Upside: you'll be able to conclusively identify what you're eating for dinner. Downside: you might not really want to know.