Open a new tab in Terminal

gistfile1.rbx

#!/usr/bin/env ruby
# Open a new tab in Terminal
# usage: tab [cmd]
# If cmd is specified, it will be run in new tab while old tab is reactivated.
# If no cmd, new tab is activated
require "rubygems"
require "appscript"
include Appscript

window = app("Terminal").windows.first
current_tab = window.selected_tab.get

# create new tab
app("System Events").keystroke("t", :using => :command_down)
new_tab = window.tabs.last

# switch back to original tab if set to run init cmd
window.set(window.selected_tab, :to => current_tab) unless ARGV.empty?

# and change dir
app("Terminal").do_script("cd #{Dir.pwd}", :in => new_tab)

# Run init cmd if specified
app("Terminal").do_script(ARGV.join(" "), :in => new_tab) unless ARGV.empty?