I'll weigh in on this one in support of jfortin and the others who support eminent domain. There is certainly a fine line in deciding when the public good outweighs an individual's interest in private property. It is much more difficult to guage this when the property will not be used for a road, park, or other public purpose, but for a private development. Still, there are private development which can generate enough good to warrant site assembly by the municipality through its eminent domain authority.
Interestingly, in Wisconsin, private property can only be acquired through eminent domain for private redevelopment through a community development or redevelopment authority. It is not a power specifically granted to a municipality. The process is to create the authority, to create a redevelopment district which must establish a finding of blight, and then initiate the eminent domain action.
I have been involved a handful of eminent domain actions. Some of the subjects have been willing sellers who wanted to proceed through the initial procedures for tax purposes. One, by far the worst of any of the properties, was one of the most difficult. We only acted after years of nothing happening with the property, despite our programs and incentives.