Sparkle is an easy-to-use software update framework for Cocoa developers.
Edit by : Sparkle is an easy-to-use software update framework for Cocoa developers.
But this Little frameworks got a lot of features packed inside! Check em out:

New in Sparkle 1.5:

Optionally sends user demographic information to the server when checking for updates.
Supports bundles, preference panes, plugins, and other non-.app software.
Dual-mode garbage collection support for any memory management style.
Supports branches due to minimum OS version requirements.
Sparkle doesnt bug the user until second launch for better first impressions.
Deep DeleGate support to make Sparkle work exactly as you need.
Sparkle can install .pkg files for more complicated products. you can free download Sparkle 1.5 Beta now.