Nokia's chat service, that's available on other Nokia platforms has now been released on Lumia phones in beta.
It allows you to stay in touch with your yahoo contacts and other Nokia Chat users. It's kinda like Nokia's version of blackberry's messenger (BBM) service.
Here are the features of Nokia Chat:
Person to Person Messaging: Reach millions of Nokia Chat and Yahoo! Messenger users across different mobile and computer platforms.
Push Notifications and Live Tile Updates: Receive new message notifications, preview new messages, and see how many notifications you’ve received – even when Nokia Chat isn’t running.
Share a Place: Send information about a restaurant, store, or other point of interest. If the recipient is also using a Lumia, they’ll see details, directions, and reviews inside the HERE Maps app.
Broadcast Your Location: Optionally include your city or neighborhood in your status message, so your friends and family know when you’re near or faraway.
Find Contacts: Scan your phone’s address book to find friends and family who already use Nokia Chat and Yahoo! Messenger.
And if you’re using a Nokia Lumia with Windows Phone 8, you can take advantage of these additional features:
Speak Your Message: Compose a message by pressing speak, and what you say will be translated into text.
Voice Commands: Start Nokia Chat by long-pressing the Windows key and saying “Chat with” and the name of an existing contact: for example, “Chat with John”.
Lock Screen Notifications: See how many Nokia Chat notifications you have on your lock screen. Start the built-in Settings app and select “lock screen” to begin.
The app is available in United States, United Kingdom, India, Canada, Australia, New Zealand, South Africa, and Nigeria for now, but should make its way to other countries around the globe as Lumia expands.
You can read more about it and download it HERE