It's not a big network, but $500,000 was spent for few results: A firm said in Sept. 2004 that they'd blanket the area, but underestimated the equipment cost. They wound up predicting three times the number of nodes would be needed, and the city wasn't prepared to let them put them everywhere they needed to. About 200 sessions a day are counted in the limited area served.
This is a key aspect often overlooked in discussing metro-scale Wi-Fi: you have to find places to put the number of nodes you need. So even if the economics worked out to put in 40, 50, or 60 nodes per square mile, you have to find the poles, buildings, and other facilities every 100 to 300 feet or so in the right spots. [link via MuniWireless]