Add a version constant and print it with --version.

cocoapods.gemspec

 # -*- encoding: utf-8 -*-
+require File.expand_path('../lib/cocoapods', __FILE__)
 
 Gem::Specification.new do |s|
   s.name     = "cocoapods"
-  s.version  = "0.0.1"
+  s.version  = Pod::VERSION
   s.date     = "2011-09-17"
   s.license  = "MIT"
   s.summary  = "A simple Objective-C library package manager."

lib/cocoapods.rb

 module Pod
+  VERSION = '0.0.1'
+
   class Informative < StandardError
   end
 

lib/cocoapods/command.rb

@@ -40,7 +40,8 @@ module Pod
     def self.options
       "    --help      Show help information\n" \
       "    --silent    Print nothing\n" \
-      "    --verbose   Print more information while working"
+      "    --verbose   Print more information while working\n" \
+      "    --version   Prints the version of CocoaPods"
     end
 
     def self.run(*argv)
@@ -58,6 +59,8 @@ module Pod
 
     def self.parse(*argv)
       argv = ARGV.new(argv)
+      raise Informative, VERSION if argv.option('--version')
+
       show_help = argv.option('--help')
       Config.instance.silent = argv.option('--silent')
       Config.instance.verbose = argv.option('--verbose')