The simplest thing that you can do to open up the Sublime Text 2 editor on your Rails project is to just type in

$ subl .

on the Rails root directory¹. A slightly better solution is to create a .sublime-project file in your project root directory, so that you may launch the editor with something like

$ subl --project my_rails_project.sublime-project

A question then arises, “How do I exclude useless directories as tmp or log from the project file?” Answer: just edit the sublime-project file this way:

{
 "folders":
 [
   {
     "path": ".",
     "folder_exclude_patterns": ["tmp", "log"],
     "file_exclude_patterns": [".tmtags"]
   }
 ]
}

(and of course you should adapt it to your actual preferences on what to exclude from your project). Note that you can also specify a “file_exclude_patterns” property to filter out some files (in my case I wanted to exclude the ctag index file).

1. to install the command line tool, just follow the docs here.