A few months ago we reviewed Parcel Tracker for Windows Phone as a solid app for seeing where your shipments are in relation to you. A new app though is in the Marketplace called 'Package Tracker' and the UI is actually a little slicker and more refined. Only downside we found is those outside of the U.S. won't get as much use as it only has four couriers on board: FedEx, USPS, UPS and DHL.
One other great feature we forgot to mention in the video is "Carrier's Contact Info" screen, giving you quick access to their phone numbers and 1-click dialing--very smooth. Overall, we really like this app and recommend it for those needing to track their stuff. The app fetches for $0.99 and there is a free trial which is limited to tracking up to three packages at one-time, making it a basically a free app for those who don't track many parcels. Grab it here in the Marketplace.