Drupal-Commerce-Quickbooks is a project mainly written in PHP, it's free.
A clone of the Drupal Commerce Quickbooks Connect Module from http://drupal.org/sandbox/stephen.colson/1100862
This is a clone of the sandbox module from drupal.org located here: http://drupal.org/sandbox/stephen.colson/1100862 that is intended for development work to enable Drupal Commerce to use quickbooks as an optional payment gateway and for accounting.
More to come...