The iPhone Simulator that comes with the iPhone OS 2.2.1 SDK is the last version to secretly have shipped as a Universal Binary; so that it works on PPC machines running Leopard. This is how to get it to run: 1. Find the SDK. The name of the disk image released by Apple is iphone_sdk_for_iphone_os_2.2.1_9m2621a_final.dmg. 2. Mount the image and open the Packages folder. 3. Open iPhoneSimulatorPlatform.pkg using Pacifist and tell it to "install" the package. 4. In Finder, go to /Platforms/iPhoneSimulator.platform/Developer/Applications and finally launch iPhone Simulator. 5. Have fun surfing with Mobile Safari or whatever edit: Removed link. Better be safe than sorry.