This last Austin on Rails meeting highlighted the latest version of Sun's NetBeans IDE. Gregg Sporar gave a good overview of all the new Ruby and Rails features in NetBeans. I am very impressed with Sun's commitment to Ruby and Rails. My favorite feature was the ability to convert javaStyleCamelCaseVariables names to their equivalent, java_style_camel_case_variables ruby style automatically.
The ability to switch easily between model,view, and controls looked very helpful.