Well if you love the idea of Messages being made available on OS X (I know I do), you’ll be pleased to find out that the Beta app of Messages has been made available for download. However your joy might be short-lived especially if you do not have plans to pay for the upgrade to Mountain Lion when it sees its release later this summer.
It was discovered by Consomac through text strings found in the App’s resources that once the beta has expired, Messages will no longer be available for OS X Lion users, and will then ask the user to proceed to the Mac App Store to purchase the OS X Mountain Lion upgrade. Naturally this will not sit well with users who may have recently paid to upgrade to OS X Lion, but unless Apple changes their mind, it seems that OS X Lion will be left out of the loop for now.
In the mean time, if you’d like to check out the Messages Beta app, head on over here for the direct download link to see if the future upgrade could be worth your money.