Google Talk or GTalk is one of the popular chat services and it comes with apps for Windows desktop. If you are using a Windows Phone 7.5 device, then you can try out GChat, a free app for Google Talk. The app is a fast, privacy-conscious client to use your favorite IM messaging service.
- Push notifications for messages
- Pinning any of your contacts as a secondary tile, with independent unread message count.
- Off-the-record conversations, with special and delicate handling