The cork is actually for examining.
If you have the good fortune to sit down in a restaurant with a wine steward, you're not going to make a great impression by sniffing the cork when he hands it to you.
In truth, he's presenting you the cork to examine. Check to see if it's all in one piece; a fragmented or moldy cork might mean a lower quality wine.
With the best wines, the cork will display the date and other information, as well.