For the people that tracking by the order number didn't work for them (Order number starts with W and you remove the last two numbers) also try to use the phone number you renewed with as the reference e.g 3231234567.
In my case I purchased a T-Mobile Unlocked model so they do not know my number that is associated with the phone, but for people renewing contracts this might work as well because some sort of reference number is always associated to a UPS package.
My order still says "Preparing for Shipment" but is in fact already IN TRANSIT.
Incheon, Korea, Republic of 10/01/2013 8:21 P.M. Arrival Scan
ZhengZhou, China 10/01/2013 4:46 P.M. Departure Scan
ZhengZhou, China 09/30/2013 4:11 P.M. Origin Scan
China 09/30/2013 6:26 A.M. Order Processed: Ready for UPS