save_chrome_url.rb

#!/usr/bin/env ruby -wKU

require "rubygems"
require "appscript"
include Appscript

chrome = app("Google Chrome")
safari = app("Safari")

chrome_tab = chrome.windows[1].active_tab

save_url = chrome_tab.URL.get
save_title = chrome_tab.name.get

safari.add_reading_list_item(save_url, :with_title => save_title)

But this in Applescript is much better:
In Alfred's Workflow, add Actions then Run Script
Select as language /usr/bin/osascript

tell application "Google Chrome"
set pageUrl to get URL of active tab of first window
end tell
tell application "Safari" to add reading list item pageUrl

The only thing was, I didn't realised it worked allready, no signs of this process in the screen (like you would see with a typical GUI macro recorder => selecting URL, switch to safari, etc...)