Accessories production date
From Mobile Wiki
Production date in Serial Number
For new accessory products the production date is not always printed separately on the label.
For all accessory products containing a serial number you can find the production week by looking at the first 4 digits:
s/n: YYWWSSSXXXXXX YY = year (08 for 2008) WW = week (03 for week 3) SSS = Supplier information X = serial running number