wp-e-commerce/WP-e-Commerce — pull request #277 by 1bigidea (2013-03-09 18:13:10+00:00)
Title: Adds new filter over provided_parameters in Add to Cart ajax action

I can find no other way to add a custom parameter to the cart items. This allows third-parties to affect the provided parameters prior to inserting them into the cart_item.

My use case: my bakery client needs to add a pickup date to the cart item