Forwarding Growl Notifications to Notification Center on Mountain Lion.
Update: If you buy the latest Growl from the Mac App store and open the settings, you can forward everything to notification center natively now.
I've been using Growl for notifications on my Mac since the very first day that I made the leap to Mac years back. It's been such an important part of my workflow that I actually get extremely annoyed when it's not installed on a Mac that I use. Much like AlfredApp I tend to forget it's not a stock feature. With the release of 10.8 it seems that Apple decided to do the wrong thing by not buying Growl and just ripping it off with their own version in OS X 10.8. As anyone with Growl and 10.8 running will tell you not everything is up to speed with Notification Center--and who knows what will be? Some apps might stay loyal to Growl.
Literally every other notification on my Mac is coming from a different provider. Transmit will notify me my sFTP upload is done on Growl and Google Chrome will notify me that I have a new email in Gmail using Notification Center. It's becoming extremely tedious and annoying to have to babysit and check two different notifications areas.
Thankfully, I wasn't the only one who had this idea and someone developed a wonderful app called Hiss. Hiss is an extremely simple app that will forward all of your Growl notifications to Notification Center with the click of a button--just one click and it's done for good. How nice. Now I can continue to support the Growl project that I have used for years and finally have matching notifications. (I say finally because Chrome not using Growl has driven me crazy for ages now)
To get started you'll want to go grab the app from the Hiss website.
Next you'll want to kill Growl, as it won't install with Growl running, what you'll want to do is fire up Activity Monitor and use the search to find Growl as shown below:
Once you locate Growl head over to the big red stop sign in the left corner labeled Quit Process. When prompted select the Quit button. No need to select Force Quit unless Growl doesn't quit with the first option. It's cleaner to just use Quit whenever possible.
Once Growl is quit fire up Hiss and wait for it to load. If it loads to a giant green light then you've successfully installed the app and as of now all Growl notifications will be forwarded to Notification Center. To make sure that this stays in effect you'll want to select Start at Login as shown below before closing out of the window.
Once you've got everything set how you want it, simply close out of Hiss and let it do it's thing. Fire Growl back up either using LaunchPad, Alfred, Spotlight, or one of the other countless ways to launch apps on OS X and enjoy!