#!/usr/bin/env ruby

 require "rubygems"
 require "appscript"
 include Appscript
 require "active_support"

 mail = app("Mail")

 accounts = {"Personal" => "INBOX", 
             "Both Pieces IMAP" => "INBOX", 
             "Exchange" => "INBOX"}

 accounts.each do |acct,box|

 account = mail.accounts[acct].get
 inbox = account.mailboxes[box].get
 messages = inbox.messages[its.flagged_status.eq(true).and(
                           its.date_received.gt(Time.now - 3.days)
                           )].get

 messages.each do |m|
 	puts m.subject.get
 end

 end

Find Recently Flagged Messages in Mail.app with appscript

mail, ruby

Ruby