Is there an iMessage client for OS X? Apple's new iMessage sends messages between accounts associated designated e-mail addresses (as well as certain phone numbers). Apple's iChat also sends messages between accounts associated designated e-mail addresses. For the most part, for example if one uses the default iCloud settings, these e-mail addresses are the same. Yet, as near as I can tell, iMessages only work between iOS devices and iChats only work between OS X machines (or machines running specific chat clients). 

If this is correct, is there a way to get around this limitation using an iMessage client for OS X, or is it possible to configure iChat as an iMessage client?
Apple has just announced OSX Mountain Lion which incorporates iMessage into the OS in the form of the Messages app. This will work in the same was as iMessage for iOS.

http://www.apple.com/macosx/mountain-lion/

You can currently download the messages beta free from Apple here