Some serial number decoding insight I've learned over the last little while:
The last four characters are the same for everyone with a particular phone. It is characters 6-8 that are unique to your phone (well, not technically unique, but taken with all the rest of the characters, they are)
Basically, you can post up 12345...9012 but leave out 678 and no one will be able to identify your phone.
Characters in positions 1 and 2 are the factory is was made in (same for all Apple products made in that factory)
Character in position 3 - I have no idea, any guesses? Perhaps a checksum digit?
Characters in positions 4 and 5 make up the production week of your phone (same for everyone whose phone was made that week)
The earliest production week stated so far in this thread has been 32. That's the week of August 5-11 as shown:
32 - August 5-11
33 - August 12-18
34 - August 19-25
35 - August 26-Sept 1
36 - September 2-8
37 - September 9-15
Characters in positions 6, 7, and 8 show how many phones into the production week yours was (so naturally, knowing this along with the first five digits will pretty much give away your serial, if the person knows what kind of phone from positions 9/10/11/12 below)
Characters in positions 9, 10, 11 and 12 - these last digits are the Apple product model. Every iPhone, iPad, MacBook, Apple TV, or Thunderbolt display of the same configuration will have the exact same last 3 (or now 4) characters. This is why one of my iPhone 5s is F38W (64GB black for at&t or carriers in Canada) and the other is F38Y - all other people with a white 64GB phone on at&t will also have a phone that ends in F38Y. It could be made in a different factory (1/2), a different production week (4/5), obviously it'll be a different phone so (6/7/8) are different, but (9/10/11/12) will always be the same.
