Now tweets can be sent and received via  MSN messenger as well. There’s a bot twitonMSN which integrates an API into twitter account and link it to your msn messenger account. To setup this bot follow the steps :

• Visit  TwitonMSN and add a contact name to your MSN Messenger. The contact is an automated bot which when you log in to your MSN messenger will allow you to connect to Twitter.
• Just type into MSN Messenger’s chat window whatever you want to. A simple message as in the one shown in the image above is posted as a tweet.
• The bot also keeps sending you every single tweet on to your messenger chat window.
• It supports following an username, replying to a tweet and also Retweet. If you drag and drop a picture file into the chat the image is then posted along with a tweet.
• Even sending a direct message is possible by typing it in the following format “d username content” .
• For a comprehensive command list type in “commands” and for help type in “help”.

From : http://twitonmsn.com/