This is a fork of stephen.colson's sandbox module: Drupal Commerce Quickbooks Webconnect https://drupal.org/sandbox/stephen.colson/1100862
The above module does not appear to be maintained and requires a number of patches (see open issues) to be usable. This sandbox includes patches for issues I have added to the original sandbox project in an attempt to make it easier for other users to leverage the great work started by Stephen Colson.
Commerce Quickbooks Webconnect is a sub-module for the Services module. It creates a SOAP server that is compatible with Intuit's Quickbooks Web Connector.
This module is currently able to export customers, products and orders to Quickbooks. This module may occasionally exhibit issues exporting data perhaps due to incompatible character sets. If you require functionality that is more reliable and commercially supported you may want to consider products such as ecc by Webgility. Due to the integration with other modules such as Commerce, Entity API and Services this module is a bit fragile. Using this module on a live store is risky though there are stores currently using and depending on it. Use caution.
The above disclaimers aside, this module does largely work and could further benefit from an active development and user community.