Developer website: Simonster.com
PackTrack is package tracking application that has the ability to track UPS and FedEx carriers out of the box. It also includes an interface for creating plug-ins for other carriers.
Version 1.0.2 adds interface improvements and adapts the UPS plug-in to work with UPS's redesigned website. Revision 2 fixes a problem with the UPS module if the delivery date is unknown.
Mac OS X 10.1 or later