http://news.sciencemag.org/2013/08/here-it-comes-%E2%80%A6-375000-lab-grown-beef-burger
So on Monday the first artificially grown burger is to be shown off. It'll be something that's gonna be silly expensive for an age, but I'd reckon in about 30 years or so it'll be the common form of meat, with actual cow meat being the pricey thing (well, it'll be the pricey thing either way, there's a hard limit on how much livestock we can keep around and maintain)