From the NY Times obit:
Ms. Jacobs['] … "The Economy of Cities" (Random House, 1969), challenged the ideas that cities were established on a rural economic base; rather, she suggested, rural economies have been built directly through city economies. After that came "The Question of Separatism: Quebec and the Struggle for Sovereignty" (Random House, 1980). It argued that Canada and Quebec would be better off without each other, on the general grounds that smaller is better.
She delved more deeply into economics and cities with "Cities and the Wealth of Nations: Principles of Economic Life" (Random House, 1984), in which she contended that national governments undermine the economy of cities, which she saw as the natural engines of economic growth.
I don't know of any school of urban planning that I'd agree with wholeheartedly, but there's much to admire in Jane Jacobs's work, especially where it touches upon decentralization and the primacy of cities over national governments. Don Boudreaux, in an incisive post on Cafe Hayek, cites this passage from Cities and the Wealth of Nations:
Nations are political and military entities, and so are blocs of nations. But it doesn’t necessarily follow from this that they are also the basic, salient entities of economic life or that they are particularly useful for probing the mysteries of economic structure, the reasons for the rise and decline of wealth.