@CpILL - To act on something once payment is initiated will be a little tricky. You can do one of a few things... probably the thing to do would be to use the submit $op for hook_order(). The problem is that for redirected payment services, you won't necessarily receive a confirmation. For example, someone could get all the way through checkout, go to PayPal to pay, and then just never complete payment. I suppose this is where the cron hook would do the clean up of carts in checkout.

@lafflam - I was looking at what it will require to add the code for removing items from the cart and it's more than a 2 minute fix. Otherwise I'd do it right now. As it is, I really want to get Alpha 7c out the door. Once I get it out, I'll add in a call to hook_cart_item() when a cart is emptied automatically, an item is removed through the update form, or a cart expires. I forgot I'd have to deal with it in all three places.