EXEC [Growl].[spQueueNotification]
   @Application = N'Test App',
   @Type = N'Executed',
   @Title = N'Test Title',
   @Message = N'Test message\nline two' -- use \n for newline

Other parameters:

-- set to 1 to clear cached Growl objects
--
@ClearCachedObjects = 0

-- The service will look for the icon in Icons folder of
-- installed service and append .png to the name
--
@Icon = 'name'

-- usually only needed if notification has to be
-- forwarded to other Growl instance
--
@Password = 'password'

-- if you want the notification to be forwarded to
-- another Growl instance, it's preferred to setup
-- forwarding in Growl itself
--
@Host = 'hostname'

-- In the rare situation that Growl is not listening on the default
-- port, you can specify the port
--
@Port = '23053'

I decided to host the project on GitHub for two reasons. a) to play around with Git and b) because it is hip
Here is the setup: Sql2Growl_1.1.zip
And here is the git repository url: sql2growl

As soon as the project is in a state I am happy with I will post more information.