Not affiliated with the developer in any way, but just ran across this app.. and WOW. This does similar thing as Prowl for iPhone - custom notifications for variety of purposes.. can integrate with Prowl, Google Voice, Twitter etc. It is much nicer than Prowl, as it's a native iPad app, with a beautiful UI.. just much more polished app, and highly customizable. Best of all, it's FREE. I have now deleted Prowl, and redirected all my Growl apps to Boxcar. Highly recommends you give it a try and leave good feedback for the devs.