Few months ago, Apple announced a new OS X for Mac, Mountain Lion. It's a brand new featuring a lot of handy tools that were presented in the iOS 5, such as notification center, reminders, and iMessage. The Beta version of iMessage for Mac is actually available on the Apple website.
This OS was originally to be released in summer but a report from AppleInsider states that Apple are now hiring and training new AppleCare employees, which means the OS will be released within weeks. So if you're planning on upgrading to the new Mountain Lion OS, I suggest you do a backup and a few maintenance to boost the performance and start fresh.