Your app will be able to update itself, not just check for new versions: it’ll read the update information from an appcast on your server, download, extract, install, restart, and even offer to show the users release notes before they decide if they want to update. [Noice!]
Sparkle – Trac
Sparkle – Trac: Sparkle is a module that developers can stick in their Cocoa applications (five-step install!) to get instant self-update functionality.
