Yes, it's been noticed. Depending on the number it will connect you to FedEx, UPS and USPS. Very handy feature. If you know it's not a tracking number, just ignore it. Also in iOS 5.
It brings up the carriers web site in Safari in a new tab.
I'm disabled and seldom leave my home. I order most everything, including food, on the Internet. When the seller sends me an email with a tracking number I just touch the number and it opens a new tab in Safari and I can track the shipment all the way to my home.
If you are interested in tracking shipments you should look at the Deliveries App