export.rb

require "rubygems"
require "bundler/setup"
require "httparty"
require "active_support/all"

class TumblrApi
  include HTTParty

  base_uri 'http://www.tumblr.com'
  default_params :email => '',
    :password => '',
    :state => 'draft',
    :type => 'regular',
    :format => 'html'
end

posts = Hash.from_xml(File.read('wordpress.2011-11-18.xml'))

posts['rss']['channel']['item'].each do |post|
  next if post['status'] != 'publish' || post['post_type'] != 'post'
  
  tags = ((post['category'] || []).uniq - ['General', 'Resources', 'RubyOnRails', 'Scrum']).join(', ')
  body = post['encoded'].join

  TumblrApi.post('/api/write', :body => {
    :title => post['title'],
    :body => body,
    :date => post['post_date'],
    :tags => tags,
    :slug => post['post_name'],
    :group => 'flatstack-group.tumblr.com'    
  })

  puts "#{post['title']}"
end

Gemfile

source :rubyforge

gem "httparty"
gem "activesupport"
gem "i18n"