I'm guessing/hoping that it means they are being dispatched from stock in the UK, although they could put them on a plane tonight and have the delivery companies sorting them for distribution by Friday.
They have done this every year and every year they seem to get it right so I don't imagine that someone has just forgotten us this time around.
O2 finally pulled their finger out and got sorted with the sim cards so I'm just waiting to get the new phone now.