Lambic is spontaneously fermented and can't be brewed outside Brussels or the Payottenland in Belgium because only that region has the right microflora (yeasts and bacteria): http://www.beerplanet.eu/index.php?cnt=10&paramID=1&typeID=4

Other beer sold as Lambic (such as Sam Adams Cranberry Lambic) isn't really Lambic: http://blogaboutbeer.com/the-case-against-sam-adams-cranberr...