Google Maps for PDA
Google Map now supports PDA's (in particular the Palm Treo with these features...
Real-time traffic — See where the congestion is, and estimate delays. (USA only)
Detailed directions — Whether you plan to walk or drive, your route is displayed on the map itself, together with step-by-step directions.
Integrated search results — Local business locations and contact information appear all in one place, integrated on your map.
Easily movable maps — Interactive, draggable maps lets you zoom in or out, and move in all directions so you can orient yourself visually.
Satellite imagery — Get a bird's eye view of your desired location.
http://www.google.com/gmm/treo to download the PRC and Hotsync
source: Google Alerts
other links: Palm Wiki
update: Google Maps Mania has more