Following on from Apple’s announcement of the forthcoming OS X Mountain Lion, Apple is giving Mac owners the chance to get a little sneak preview of one of the new features, by making the Messages beta available as a free download (click on the link below to get it). When you install Messages on your Mac, it will replace iChat, although your iChat services will still work, so don’t panic! Basically what Messages does is bring iMessage to the Mac, to bring it in line with devices running iOS 5, namely the iPhone, iPad and iPod touch, which seems to be the main thrust behind OS X Mountain Lion. Main features of Messages include the ability to send unlimited iMessages to any Mac, iPad, iPhone or iPod touch, as well as being able to start an iMessage conversation on your Mac and continue it on your iOS device. You can also use it to send photos, videos, attachments, contacts, locations and much more, or launch a FaceTime video call. According to Apple, Messages supports iMessage, AIM, Yahoo!, Google Talk and Jabber accounts.
Source: Apple - Mac OS X - Download the free Messages Beta.