(from the 5.x.4.x-dev version downloaded March 23rd 2008)

warning: include_once(sites/all/modules/ecommerce/product/product.inc) [function.include-once]: failed to open stream: No such file or directory in /modules/ecommerce/ec_checkout/ec_checkout.module on line 358.

has product.inc been renamed or is it simply missing from the download tar?