NopCommerce now has Web Services ! API to manage your Nopcommerce Site.

Release Notes – nopCommerce 2.20 (October 11, 2011)
http://www.nopcommerce.com/releasenotes.aspx
Significant performance optimization.
One page checkout.
‘Web service’ plugin (Web Services API).
RTL (right-to-left) support.
Added category and manufacturer templates.
Allow store owner to manage address fields on ‘Register’ and ‘My account’ page.
Added a generic event system.

 

Free API Web Service for NopCommerce
http://usasupportcenter.com/products/19-free-api-web-service-for-nopcommerce.aspx