Prowl: Growl client for the iPhone - Any notification over push

You can push anything, server notification, facebook notification, twitter replies or push mail.. as it is based on Growl. Pretty clever!<p>I wonder how it works out for the dev if users use it heavily for years paying only a one-time 3$...

Still on the fence as to how useful this will be, given that you either need:<p>a) A Growl-enabled computer running and connected to the Internet; or b) Your own server somewhere making API calls to create the push notifications.<p>It might work for iTunes Store developers to get cheap pushes to their customers, but other than server notifications (i.e "Server A is down, please ring so and so"), I'm not sure how useful this would be to the general public.