Prey Fetcher isn't operating anymore and the code is out-of-date/broken.
But you can use it if you like.
Push your tweets to your iPhone
Prey Fetcher was a free and open source service that pushed new tweets and direct messages to your iPhone, iPod Touch, or iPad. It requires Prowl, an iPhone Growl client. Prey Fetcher uses Twitter's REST and Streaming APIs to deliver fast list notifications and instant notifications of DMs and mentions.
This program is free software; it is distributed under an MIT License.
Copyright (c) 2011 Matthew Riley MacPherson.