The popular notification management tool Growl has been updated to add full support for Apple's Notification Center in Mountain Lion.
When Apple introduced its notification service in Mountain Lion, its functions directly conflicted with those of the popular Growl software, resulting in duplicate messages being presented for application alerts and other features. While one could temporarily disable Notification Center or quit it altogether if desired, this approach is not an optimal solution.
The Growl developers have just issued a new version of Growl that is compatible with Mountain Lion's Notification Center, so if you would prefer to continue using Growl after upgrading to OS X 10.8, then you might consider installing this latest version.
Even though both are notification systems, Growl offers a few desirable options that are not present in Apple's Notification Center, including customizing the look and feel of notices, various behaviors for displaying and managing the notifications, especially for those who are visually impaired. It can also be implemented in scripting environments such as AppleScript, making it easier to use in unique circumstances other than Apple's notification options.
Growl 2.0 is available from the Mac App Store for $3.99.