Does anyone know if I can concatenate text into a body field on a sales order from a value on each item line, in a work flow? Or is there a way to do this with a formula field? ie, So has 3 items, want to list the class of each item in a single field

Yes you can and you have to use the concatenation formula in SetFieldValue action which is executed in Action Sublist Group. Don't know it exactly by heart but it would look like this: {cust_bodyfield1}||' '||{line.description}