If you enter the delivery address details and before sending/submitting the order, if you move away from this page, the information that had entered is lost.
ulysses - no it is not good idea. if someone use internet cafe then someone else will get this informations
Treewood - fair comment about internet cafe - but surely the session or cookies could be destroyed at the end of submission. My only concern is that after you have entered the information, before submitting if the user goes to any other link on the cart, they immediately lose the information that was entered.
ulysses - hm... it seems ok but we must think how to do it because if someone click to another link then form will not save and session will not save data. maybe java script will save that ....