以往要傳送訊息，你大概會需要透過第三方的服務供應商，且通常會收取費用。自 Mac OS X 10.8 Mountain Lion 起，您可以使用內建的「訊息」程式。透過「訊息」程式，您可以傳送免費且數目不受限制的安全訊息，包含文字、圖片、影片、檔案和聯絡人資訊，藉此傳送訊息給其他使用 Mac、iPhone、iPad 或 iPod touch (裝有 iOS 5 或更新版本) 的親朋好友。最棒的是，您可以從 iOS 裝置上繼續進行對話。
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1. From the Messages application menu, choose Uninstall Messages Beta….
2. A dialog will appear, asking you to confirm uninstallation of Messages Beta and reinstallation of iChat. Verify that you wish to do this.
3. Restart your Mac when prompted.
跟先前 FaceTime 一樣，你不用等到下一版的作業系統推出才能在 Mac 上使用這個新應用程式。Apple 現在提供 Messages Beta 供使用者下載試用。
And Messages brings iMessage to the Mac — just like on iPad, iPhone, and iPod touch running iOS 5.
Apple sees a fundamental difference between software for the keyboard-and-mouse-pointer Mac and that for the touchscreen iPad. Mountain Lion is not a step towards a single OS that powers both the Mac and iPad, but rather another in a series of steps toward defining a set of shared concepts, styles, and principles between two fundamentally distinct OSes.