That's a topic I really fancy : turning skyscrapers into farms (aka "vertical farming"). That's impressive. There is now a website about it: Vertical farms:

The concept of indoor farming is not new, since hothouse production of tomatoes, a wide variety of herbs, and other produce has been in vogue for some time. What is new is the urgent need to scale up this technology to accommodate another 3 billion people. An entirely new approach to indoor farming must be invented, employing cutting edge technologies. The Vertical Farm must be efficient (cheap to construct and safe to operate). Vertical farms, many stories high, will be situated in the heart of the world's urban centers. If successfully implemented, they offer the promise of urban renewal, sustainable production of a safe and varied food supply (year-round crop production), and the eventual repair of ecosystems that have been sacrificed for horizontal farming.

There is a whole essay about it here. In addition, a nice project that concretize this idea:"The Living Tower" by Pierre Sartoux and the workshop soa architects in Paris. : Why do I blog this? this is an intriguing project I find interesting, I am just wondering about the problems it can foster... Connected Pasta: I already blogged about this pig farm in a skyscraper.