We utilize Point of Sale software in our brick and mortar store. The next upgrade to this software will allow for XML feeds from website shopping carts. Is there a contribution or mod for Zen Cart that would allow this to happen?

It would work both ways: bringing new orders from Zen Cart into the POS software, and also updating products, customers and orders from the POS software to Zen Cart.

I've done some searching on XML and RSS, but couldn't find anything.