Growl, the notification system for Mac OS X, was recently updated to version 1.3. While "dot updates" to apps usually don't signal a major change, that's not the case with the latest version of Growl. In a post on the Growl blog, the team described the major changes that have taken place:
Growl is no longer free. The app has a full-time development team, and all of the money made from the sale of the app on the Mac App Store goes toward supporting the continuing development. Growl is available for US$1.99, and the team reported that without moving to a paid app model, development would have ceased. It's still, however, an open source project.
Growl doesn't have to be installed for you to get notifications. When developers update their apps to take advantage of Growl 1.3, Growl no longer has to be installed for users to get notifications. As the team puts it, "Think of these updated applications as Growl, and the Growl application as Growl Pro. The Growl 1.3 SDK includes a framework which can display a notification, even if Growl is not available."
Growl 1.3 supports sandboxed applications. Sandboxing is becoming a requirement for any application on the Mac App Store, and would have broken Growl had the team not made changes. The team says that Growl 1.2 and earlier will no longer work with sandboxed apps.
Out-of-date apps don't work with Growl 1.3. Some apps will need to be updated in order to work with the new version. Developers can contact the Growl team for assistance, and users can download Growl Version Detective to determine if an app works properly with Growl.
It's still Open Source. The team says that Growl "will remain Open Source for as long as people want to be able to modify the code." The source code is available at their Google Code Hosting project under the BSD license.