Each time a non-logged in user hits their shopping cart, they are prompted to re-select their city and state and re-enter their zip code in order to get updated shipping estimates.
Has anyone already done this? if so, can you post a link to code?
Really? No one thinks this is crazy to require a customer to re-enter their country, state and zip code every time they go back to their cart just to see how much shipping costs? And then if you are using customer accounts and someone is logged in, it will always default back to their account address even if they change the Country/State/Zip in the shipping estimates function of the cart.
The Shipping Calculator provided by Shopify is a convenience, not a necessity, and as such, it seems to have been released to support a certain use pattern and does so fairly well. A customer gets to check a rate before checkout, and get an idea on shipping costs.
If you need accurate shipping off the beaten track of FedEx and UPS, you'll be using your own Shipping Carrier rates anyway, and hence you'll have no choice but to hack in your own Shipping Calculator too.
You can hack the Shopify one as much as you want and need to! It is single call to a server with an established and defined API setup. If you want to play with cookies and make it super duper better, go for it! No one will stop you and in fact, if you like what you do you could share that with everyone!
That is kinda the point when playing with open source stuff. Good things usually come of it.