IM+ with Push ($9.99; direct iTunes link) is the first multi-protocol chat client for the iPhone and iPod touch to support push notifications for both Twitter and Skype, alongside other protocols that had been supported by BeejiveIM, including AIM/MobileMe, ICQ, Google Talk, MySpace IM, Facebook IM, Yahoo! Instant Messenger, MSN/Windows Live, and Jabber. IM+ offers both landscape and portrait mode typing of chat messages, the ability to send images, voice recordings, and location information to chat buddies, and the ability to stay logged in to your chat services for up to three days after closing the application.

If neither Skype nor Twitter are of interest to you and you don't necessarily want or need the push notification functionality that is shared by both BeejiveIM and IM+, then you should try downloading the free ad-supported IM+ Lite (Free; direct iTunes link), which can still manage all the multiple chat protocols that the full version of IM+ can.