Yahoo has updated its Messenger app for the iPhone, bringing with it video calling.

The feature will work between any two Yahoo (or other compatible) Messenger clients, whether that be iPhone 4 to iPhone 4 (as you'll need a front facing camera, obviously), iPhone 4 to Android device or iPhone 4 to PC or Mac.

The other big selling point, although it's actually free, so it doesn't really need selling points, is that it works not just over Wi-Fi, but over 3G as well - take that FaceTime (and take that to your limited data plan as well).

You can also make plain old voice calls, if you'd prefer, and all of the regular Yahoo Messenger inclusions are still there such as instant messaging, SMS functions and Windows Live integration.

The update also adds multitasking capabilities, so you can leave the client running in the background and never miss a message.

If you live in the States (or France, Germany, Spain or Singapore) you'll also be able to make cheap calls to phone numbers using your Yahoo Voice Phone Out subscription.

The updated Yahoo Messenger app is in the App Store now, and won't cost you a dime.