Godaddy tries to sell expiring domains on TDNAM.com. For the first few days after expiry you can still renew it. Then comes a period of several weeks when you would have to pay an extra fee but you still can get it back. Unknown (probably) to you, at the same time they are taking bids on the name at TDNAM. If there are no bids in the auction then there is a few days period when they try to sell it for $5 + registration fee. All this time you could pay the fee (I think it is about $100) and get it back. If you do not get it back and no one bids or buys it it goes back into the pool. Then the tasters pass it around, but that is another story.
Edit-- you may know all this, but I am not sure what you are asking. the whois, I think, is always extended when the name expires, only to go away at the end of the grace periods.