GMail knows FedEx?

Over the holidays, I ordered a package online. Like many online retailors, they sent me an email confirming my purchase, and another email later with the tracking number for my package. I just noticed (as I went back to get the number to see where my package was), that GMail recognized it as a FedEx tracking number and provided a link on the right edge of the page, over with the advertisements.

Frigg'n cool.