Newly included in the Wolfram Language is the ability to send "tweet" using the SendMessage function. Its syntax is straightforward:
SendMessage[ "Twitter", "A tweet from the Wolfram Language on the Raspberry Pi!"]
Evaluating this will bring up an authorization dialog (once) to allow the Wolfram Language to send tweets on your behalf:
Click on 'Done' after entering the access key and the tweet will appear in your twitter stream: