AIM, Gchat, FaceTime and iMessage -- too many ways to communicate between too many different devices. Not anymore. The new Messages app -- available as a beta from OS X 10.8 Mountain Lion -- fixes that. This is how our fingers will talk now.
Messages replaces iChat as your Mac's default IM client. You can download it here, and the only thing you have to adjust to is a new Messages window, which serves as a master command centre for textual dispatches, tying in everything Apple's been doing with instant messaging with existing services. You can start a FaceTime conversation using the same program you use for AIM. Or Google Talk. Or Jabber. Want to text your friends, and you're sitting at your laptop? No need to pick up your phone -- just use Messages and send unlimited iMessages, just like you would on your handset.
One wrinkle is the matter of accounts. As much as Messages is wonderfully coherent, every time you select a pal to chat, you're confronted with a panoply of options: AIM, Gchat, iMessage (with a phone number), iMessage (with an email address) and possibly more. There's also some weirdness with FaceTime not working correctly -- why can I only send the invite to Matt's phone when he's also using Messages? -- and duplicate notifications on my laptop and phone. But remember, this is a beta. Of the future.
This is, fundamentally, a wonderful consolidation of talking. It's also setting a course for the future of how we talk without speaking. People are massively more available no matter where they are or what gadget they're hands are on, the stratifications melting away. With one system that covers every piece of technology you own, the days of worrying about texting outside of your wireless carrier, finding your friend's screen name, or waiting for someone to sign into Gchat are gone. If you want to be, Apple will let you be reached everywhere, and reach anyone from anywhere, more or less seamlessly. All you need is a phone number or email address, and you're plugged in. The ways this makes AIM and SMS look relatively archaic should be more than apparent.
So yes, Messages marks a strong (possibly fatal) attack against AIM and SMS. AOL's old standby has always been the gold standard for iChat, and texting, it goes without saying, has been the ubiquitous way we message someone on their phone for over a decade. Now it's all one stream. iMessage my computer, iMessage my iPad, iMessage my phone. It doesn't matter. Texting is now IMing and vice versa.
But wait, what if your friends use... Android? You'll be second class citizens to one another, it seems. The Messages app is the apotheosis of iMessage, incentivising that over every other way of sending a message. Likewise, if you're on Android, Ice Cream Sandwich makes Google Talk an alluring place to subsume all of your chatting. We've now got a two-party universal IM system in a state of enmity, and as both become smoother and more expansive, the necessity to choose sides might make communicating harder with some people as it makes communicating much more graceful with the rest. Messages is a decent interchange between the two sides of the rail, but it makes the opposition more vivid (and antagonising) than ever. Even in beta, it's already great, but like everything else in futurity, it might not turn out wholly good.