I have mostly worked in the iPhone Simulator, but in this case you will miss out on testing some of the device's resource limitations. I have had issues both with a native application and a mobile web app where I had smooth sailing in the simulator but then had crashes due to memory limitations on the actual device. Also, I have run into some things (maps) which run great in the simulator, but are crap on the device. While the simulator is still hugely useful and does allow you to fake an out of memory call, it's definitely not complete (in this case). Actually, I bet this is a Simulator vs. Emulator issue. I see that the Palm webOS Emulator runs in a virtual machine, and I am able to get some slow map performance out of it. If it supported multi-touch and rotation, it would probably be a great testing environment. For now, I'll just keep an iPod Touch on my desk. Jason