This program is great in my opinion. Even it is 1.0 (actually 1.1 is out already) state, it add a lot of features that a text editor doesn't have. My top favorites include:<p>1. Refactoring, especially really simple ones like rename method are highly useful.<p>2. Built in local history including side by side diffs with your version control system.<p>3. Middle mouse to 'jump to source'. Ever come across a method and go 'WTF is this?'. One click and you can jump right to the Ruby or Rails method source code. This can be extremely helpful for new developers learning RoR.<p>4. Integrated testing support to run single tests within the UI. (Textmate does have this too)<p>And last time I checked, Textmate seemed to be a pretty popular text editor with the Ruby community, and that runs about $60 US currently. Unless your time as a developer is valueless, laying out $100 can easily be justified if it saves you exactly 1 hour of productivity over its life time.
Paying for good tools that save time is smart business.<p>Given how amazing JetBrains' IDEA product was for the Java IDE world at the time, I can only imagine how much better this tool will get over time, especially if the Ruby Community starts using it.
I'm liking RubyMine and 1.1 has support for Cucumber. It's not as polished as Textmate, but it has light years more functionality. Split window, basic refactoring, search that doesn't blow, etc.