One of the best things about the iPhone 3.0 software is it will finally make instant messaging viable on the platform. That’s because with Push Notifications finally working, you no longer will have to have an instant messaging app open all the time to receive messages from it.

Of the instant messaging platforms, Yahoo Messenger is one of the largest, with millions of users. So far, it hasn’t been represented at all on the iPhone, while rivals like AOL Instant Messenger (AIM) have. But tonight the company announced an iPhone app at the CTIA Wireless conference in Las Vegas. It has also posted a demonstration video on its blog, which I have embedded below.

It looks pretty slick, but I have to wonder if users won’t opt for one of the IM apps that supports connecting to all of the various IM networks, like Meebo’s app will. Yahoo smartly touts its app’s ability to bypass the ridiculously priced text messages on the device, something which all of these IM services with Push Notification enabled could help change.

For now, it looks like the app will work even without Push Notification, by keeping you signed in to the network even when you exit the app. Then when you come back, you can see your messages. This is similar to what AIM and other apps of this nature do, but Push Notification will be much more powerful.

Yahoo didn’t give a date for when the app would launch, but the iPhone 3.0 software will be available this summer.

http://vimeo.com/moogaloop.swf?clip_id=3951867&server=vimeo.com&show_title=1&show_byline=1&show_portrait=0&color=00ADEF&fullscreen=1
Yahoo! Messenger for the iPhone demo video from Yahoo! Messenger on Vimeo.