There’s a slew of instant messaging apps available on the App Store, both free and paid. While many of the paid apps offer tons of useful features, I think Palringo Lite is one of the best free apps available. It will give any of the paid apps a run for the money. It supports the following services: Facebook Chat, MSN, ICQ, Yahoo, Google Talk, AIM, iChat/MobileMe, Jabber, and Gadu-Gadu. It supports picture and audio messaging, as well as location support. Push notifications allow you to receive messages even after you close the app. I think the only thing it’s missing is video chat, which would be practically impossible with the iPhone’s rear-facing camera.
Some screenies:
