Last week, without a lot of fanfare, Apple  released the beta version of its new Mac chat program, simply called Messages. Messages also happens to be a sneak preview application of what's to come in the next version of its operating system, Mountain Lion—to be released later this summer.

The following is a basic overview of the chat program and what you should consider before downloading and installing it.

Downloading Messages

You access and download Messages Beta not through the Mac App Store, but directly from the Apple website. It requires running OS Lion (10.7.3) on your Mac and that you have an Apple ID. In the initial developer preview of Mountain Lion, there are reports that Messages does not work with some older Macs, like the 2006 iMacs, even though those machines are running Lion.

There have also been reports that the full version of Messages will only work in Moutain Lion (OS 10.8) when it is finally released.

Syncs With iOS

If you download and install Messages on your Mac, it will entirely replace the existing iChat application but retain your Buddylist of contacts and your existing iChat accounts. Perhaps the most significant feature of Messages is that it syncs with your other Macs or iOS devices, and you can send and receive unlimited free messages between these devices.

Apple says Messages supports other IM clients, including AIM, Google, Talk, Jabber, and Yahoo Messenger. But in a few test cases I performed, messages sent as IM's to YahooIM and GoogleTalk users did not get delivered. Nor did I receive messages from these recipients.

Also, sending SMS messages to other non-Apple users resulted in many error messages (indicated by a red bubble with an explanation point.)

If on the other hand you're sending messages to other Mac and iOS users, similar to using Messages on your iPhone, your instant messages will sync between the Messages client on all your open devices. So you can say start a conversation with someone while at home on your Mac, and then pick up and continue that conversation on your iPhone or iPod touch.

It is, however, a little annoying to have the same messages you're posting on your Mac pop up on your iPhone which may be sitting next to your computer. There should be a way to temporialy disable syncing between devices.

Basic Features

Messages is similar in many ways to iChat and the Messages app on iOS devices. You can send photos, videos, attachments, contacts, locations, etc, for free to other Messages users.

As with iChat you start a message by clicking the message icon on the left side of Messages (or use the keyboard shortcut, Command+N) and then type the recipient's address or phone number in the To field. You can also click the blue + button and access names from your Address Book and the Buddies list started in iChat.

When you right- or Control-click on the name of a user in the left panel of Messages and select Show Info, which is under the Profile section, you will see a list the chatting capabilities for that selected user, e.g. Chat, Inline images, Chat Rooms, Offline messaging, Send Files.

Messages uses the FaceTime program for video chat, and it too only works with other Mac and iPhone users.

Apple says that you can share screens with other Mac, Jabber, Google Talk, and Bonjour users. But in my tests it didn't work, not even with the Mac users I contacted.

If you poke around in Messages you will see that many of the user interface features can be changed, such as customizing the font styles and size, changing the messages from bubble to box format, and how you want messages listed.

As Messages is in its beta stage, many of its features may not initially work. However, it is a great step forward that Apple is bringing SMS and improved iOS integration to the Mac, which is basically the intent of the Mountain Lion upgrade.

If you decide to install and use Messages, let us know what you think of it.