Jamais Cascio over at Open the Future has an informative post on various urban future scenarios, with links to several analyses, including:
Ultradense Cities in Science Fiction
Saudi Arabia: Urban Experimentation in the Heart of Islam
SimCity Goes Open Source
Worth a read - over at 'Data Points: Urban Futures'
See also Cascio's article on weather warfare and political/military geoengineering over at 'Battlefield Earth' (another great article).