With the launch of the new iPhone 3G S, the first push IM client for the iPhone has been launched and is now available in iTunes. AIM is the first client to roll out with the new push notifications. The app can remain running and messages, alerts, sounds, and icon badges, and all other notifications happen as they occur. You can customize how the alerts are displayed, you can choose to have them play a sound, a pop up tool tip, or have an icon badge, or any combination. The downside to the app is the free version (iTunes) is supported with advertisements. The full non-ad version costs $2.99 (iTunes).