More information about Asus can be found in this thread:
http://forums.overclockers.co.uk/showthread.php?p=18832269
You will see that at least one customer has now received his replacement Asus board, and mine arrived just after lunch today.
As has already been mentioned, Asus despatch the new B3 board the same day as they receive the old one, so you should only be without one for a couple of days.
They are using UPS and are shipping directly from the U.K. (Hemel Hempstead actually!) and I have found them to be more than helpful, with a tracking number supplied for both the delivery & collection, which is always good to have.