Linking Arduino With Twitter
The new Twitter 1.1 API requires OAuth authorization over SSL, for which Arduino is under-powered.

You will need to write a proxy application, which would parse the tweets and then send a RGB color value to your Arduino.

You should split your project into three parts.


Retrieving tweets with the Twitter API.
You can get some library to do it for you.
Communicating with your Arduino.
Just try to send an arbitrary color to your Arduino over internet.
And finally joining first two pieces of code together.


And if you get stuck somewhere, you can always ask for help here on StackExchenge.