Juzer Burhani

If you have been looking for a free, light and feature-packed instant messaging client that works with most popular IM clients like MSN, Yahoo! and Google Talk, then do give Instant-t a try.
Instant-t Messenger is an easy-to-use, fully-featured and a very secured instant messaging client suitable for enterprises where you need to have access to multiple IM. It comes in two versions, a desktop client and a web-based version. Both of them allows you to chat with MSN, AOL, ICQ, Yahoo! and GTalk contacts and are developed to fully improve internal communications. It also features multiperson video chat room with your friends on other IM networks.
Features

• New multiperson video chat
• Interoperability with Google Talk
• Multiple ways to see your contact list
• Support for tabs in message window
• Contact list search
• Rename contacts on all networks
• Display picture
• Custom status text
• Webcam as display picture
• Improved toaster (online notification)
• New skins (Classic and Dusk

It contains no advertising, spyware and is absolutely free to use!
Download
Download Instant-t Messenger 5.0
Web-Based Version
You can access the web-based IM from Instan-t aka Instan-t Express from here.

The newfound bonhomie between Yahoo & Google is not just about AdSense, the two companies are connecting their popular IM clients as well.

That means you no longer require any third-party hacks to chat with your Yahoo! Messenger friends using Google Talk and vice-versa.

From the PR: “Yahoo! and Google agreed to enable interoperability between their respective instant messaging services bringing easier and broader communication to users.”

Microsoft & Yahoo already offer interoperability between Windows Live Messenger and Yahoo! Messenger so this gives Yahoo! users the best of both worlds – they can talk with friends on Google Talk as well as those who on are MSN Messenger.