Slashdot has the story that Microsoft and Yahoo are to allow users of their instant messaging (IM) networks to talk to each other cross-network. This means that if I’m on Windows Live Messenger, I can talk to my friends on Yahoo Messenger directly from my account.

At the moment in the US, AOL Instant Messenger has the dominant market share, and this move could easily be seen as a collaborative move by Microsoft and Yahoo to try and tip the balance in favour of their networks, and share advertising revenue amongst the two services.

One of the interesting things about instant messaging is that the network you use is usually determined by what network your friends are on. It’s this that has probably brought AOL to the dominant position in the USA. With this announcement, this might no longer be the case, but will we see people switching networks? I’m sceptical, I don’t think people are generally prepared to switch networks unless there’s a good reason. This might be a convienience if you’re already on Windows Live Messenger or Yahoo Messenger, and for Microsoft and Yahoo it might be nice, but I doubt it will change AOL’s position as market leader (in the US at least).

UPDATE: I’ve had a little play with the integration (which I need to point out is beta), and after activating the connection service in both Windows Live Messenger and Yahoo Messenger, it works fairly transparently, apart from a small Windows Live or Yahoo icon when talking to people on the opposite network. You can sign up for Yahoo here (click Join Up) and using the latest version of Windows Live Messenger just add your Yahoo contacts as normal.