AT&T is launching the Ogo today, a little device targeted for teenagers that has IM, email, and text messaging, but no incorporated phone. There's also bluetooth so you can share files with other bluetooth enabled devices. While the Ogo itself is pretty cheap, just $99, the monthly charge is fairly hefty, $17.99 for unlimited text messages, email, and IMs on either AOL, MSN, or Yahoo. There's a $3 monthly charge if you want an additional IM service. This does have a color screen, but there doesn't appear to be a web browser so all you'll really get to do is see those big flashing smilies in full color.
I think I'd pick the Zipit Wireless Instant Messenger over the Ogo, for a dedicated IM machine, even though the Zipit is dependent on finding a wifi connection. Same price, no monthly fee.
From PC Mag.