Perfect for the IM addict, the Aeronix Zipit Wireless Messenger is a dedicated IM machine that supports all three major IM networks, and can handle up to 99 simultaneous conversations. It comes with a full thumb keyboard layout as well as quick-access buttons for emoticons and buddy lists. It uses 802.11b WiFi for connectivity, which means you don't have to pay any subscription fees. And here's a bonus for open source aficianados; the Zipit is an embedded Linux platform.
Zipit Wireless Messenger [Zipit via Linux Devices]