Mine has landed today and, according to the wife, it's an October 06 console where mine was Nov 05. It took around 20 days.
Whats more interesting is that mine had been opened and severly hacked around with when I was trying to fix the 3RLOD problem using the info on the net. You could clearly see where I had used a screwdriver to split (literally, half the pins were broke off 'cos I was frustrated) the case open.
So, either they are happy to replace 360's that have been opened for modification / fixing, or, much more likely, they aren't even checking them when they get them off the lorry.