Wew cool this Twitter and ustream mashup. I was able to mashup my Twitter tweet on my live streaming video in ustream. If I am live you can see it in this posting or my ustream channel. For this mashup I installed a php script and an image on my server. This script pulls the last twitter tweet and saves it as an image.
After that I installed RoboTask which pulls the image from the server to my hard disk.
Finally I installed Webcam Max which pulls the image from my hard disk and shows it as an effect. You can see it on this picture at the bottom of the video. So this text is my last tweet.
You can read more on this blogposting on Web Video Doctor
Please let me know if you see how this can be of any use.