We have a client who sells both perishable and non-perishable items. They would like a shopping cart solution that allows them to tie specific shipping methods to individual items. For example, let's say they use UPS. Item A is perishable and can only be shipped via Next Day Air. Item B is also perishable, but could go 2nd Day Air or Next Day Air. Item C is non-perishable and can ship via UPS Ground. Is there a cart solution out there that allows them to specify what shipping options are available on a per-item basis?
Don't think this is the answer you are looking for, but if you use the shipping API of either USPS or UPS, this is easily managed. The API is a programming interface that allows a cart to connect to get real-time pricing bsed on the variables you send. Normally that's weight, parcel dimensions, etc., but in these instances you would just add these values when posting to the API and only the appropriate shipping options will be returned.
So, any cart that uses the shipping API's **should** support this feature. To find out if it supports these particular variables, you'd have to ask the vendor of the particular cart you're using.