From Houdah Software Sarl.:
Type2Phone turns your Mac into a Bluetooth keyboard for your iPhone, iPad or Apple TV. Type text on your keyboard and it will appear on your iOS device. Prepare text on your a Mac and then paste it to your mobile device. Send tweets. Update your Facebook status. Chat. With the comfort of a full keyboard Reply to emails on accounts configured only on your iPhone. Use AppleScript to automate text input to your iPhone.