There are two versions of this project. The first one uses a Perl script running on the PC to get tweets via the Twitter API. It then forwards these on to the Arduino which is running code to scroll the tweets. The second version uses an Ethernet shield to gather data directly from Twitter. This creates a stand-alone Twitter scroller.
There isn’t really much to mention about the USB project. The source code includes both the Perl script and Arduino PDE which should directly dump onto your Arduino device. It was written for Arduino UNO. Included also is the 4-bit LCD driver that I use. There is a video on YouTube of the USB version:
I’m still working on this project.