Push.ly
Push.ly, is a free mobile service, which allows its users to track mentionings of their nicknames on Twitter and then delievers the findings to the mobile phone.
One can follow up to 30 accounts in real-time. Push.ly uses Notifo to deliver push notifications to mobile devices.
Short link: http://name.ly/~8PIF$7c
Tet another Tweet.ly service: http://converse.ly/