I learned about this trick a few weeks ago as I was reading through a local Mac User Group. Wouldn’t you like to know when and where you Mac was built?
coconutIdentityCard does just that for you. As the screenshot shows below, you can see the location where and date when your Mac was presumably created.

I’m not sure as to why it would place the date of creation on a particular week and not on a particular day. My guess would be that computers are released in batches, and the date indicated may be the date when that current batch was being assembled.
It can also check the same information about your iPod and other Apple products that use the same 11-character serial number format.