Last week I went to Chicago and made it to Millennium park which has two really exciting pieces of public art. The Crown Fountain by Jaume Plensa and Anish Kapoor's Cloud Gate (Also called 'The Bean')
The Crown Fountain is two glass brick towers that face each other and features video of about 1000 different Chicago residents. There is also a spout where water pours out from the 'mouth' of the residents every once in a while. It's really entertaining to watch people interact with the towers and to see residents who may have been filmed check out the towers to see if they'll show up on the glass block screens.
Kapoor's Cloud Gate is perfectly placed to almost fully reflect the grand architecture of Michigan Avenue on one side and the park on the other.
There's a good article on the resurgance of public sculpture in the New York Times today. It also does a kind of drive-by review of the Koons show (also in Chicago).