It would be good to retain the shipping quote selection if an error occurs. Now, if there is an error on the checkout screen (bad coupon code, missing payment info etc.), the screen is redrawn with an error message -- but the shipping quotes are gone along with any shipping selection the user has made. So, the user corrects their mistake but forgets to recalculate the shipping. Then after submitting another error occurs -- you have to select shipping -- which the already did the first time.

I'd suggest this info get retained between screens because it is very confusing for users. Ok, thanks guys.