Just saw this on AdSense blog: I guess now PIN's will take more to arrive since now it's sent to al lot more of people.
They send it to your physical addres so they can verify that you actually live there, so they can send your payment to you.
Hehe i saw this message 3 days back and already posted about that here. http://forums.digitalpoint.com/showpost.php?p=6332781&postcount=6 DON
I agree with thewolf.. they want to make sure the account holder stays at the place so that they can send payment.. Regards,