In addition to the announcements about Apple’s next operating system Mac OS X Mountain Lion, the company rolled out a beta edition of its iMessages chat app on Thursday.

Apple previously launched its iMessages for the iPhone and iPad as an answer to Research in Motion’s popular BlackBerry Messenger service. The app lets you send text, pictures, contacts, and video over 3G and Wi-Fi connections to anyone with an Apple ID or one of the other third-party messaging services. One big perk to using Messages is that it doesn’t charge you for each individual message, similar to the way wireless carriers do with SMS. Now, Apple wants to bring this functionality to the desktop in an effort to bridge the gap between conversations on mobile devices.

The new Messages beta replaces Apple’s native OS X instant message client iChat, which aggregates the IM functionality from several third-party services (Google Chat, AIM, Yahoo Messenger and Jabber accounts) into a sole location. Personally, I prefer using other IM applications (such as the open-source Adium) so I never paid much attention to iChat anyway, which I’m guessing the majority of other Mac users did as well. That said, I might actually use the new Messages app in addition to my preferred IM desktop client.

Unlike iChat, the Messages app doesn’t just focus on communicating with people who appear online at the same time that you do. Both the new desktop app as well as the iMessages iPhone/iPad counterpart emphasise short back-and-forth responses similar to SMS conversations. The app still has a buddy list of contacts, but the chat window looks nearly identical to the iMessages iOS apps.

People who never use instant messenger but frequently send texts will probably end up using this app. It’s also likely that far fewer SMS messages will get sent over the course of time, especially if you consider the rising cost of texting plans. That’s a good thing for Apple and a very bad thing for wireless carriers, which draw a large amount of revenue through texting services.

The Messages beta app is available now via Apple’s official site, with the full release due out with the launch of OS X Mountain Lion. — Tom Cheredar, VentureBeat