From the 'About' page: > Shoes 4 is a total re-write of Shoes. It's being done in JRuby with best practices. It re-implements the original Shoes 3 definition o

From the 'About' page: > Shoes 4 is a total re-write of Shoes. It's being done in JRuby with best practices. It re-implements the original Shoes 3 definition of Shoes in a pure Ruby friendly way whereas Shoes 3.x is more difficult for Rubyists to modify since it has C and Objective-C components and a build process that is less than easy to understand. Shoes 3.2 also has hardware costs and web hosting costs which makes if difficult for many developers to duplicate.