Killian Bell for Cult of Mac:
If you haven’t already installed the Messages application on your Mac, you will now have to wait until OS X Mountain Lion is released next month to get your hands on it. The Messages for Mac beta, which was released back in February after Apple’s initial Mountain Lion preview, has now been pulled by the Cupertino company.
It seems like a reasonable thing to do under the circumstances. Mountain Lion is only a month away from release, so if you’re not using Messages yet, you’re going to need to be just a tiny bit patient before you do.