The Official Google Earth application for Android arrived in Android Market today. Although only users running on Android 2.1 can download the application, so you have to have Nexus One or a rooted Android phone with 2.1 on-board.
Description from Android Market: Use Google Earth to explore the world from the palm of your hand. Fly around the planet with the swipe of a finger, as you view the same 3D imagery available in the desktop version. Search by voice for cities, places, and businesses. Browse layers of geographic information including roads, borders, places, photos and more