A developer has created a service that allows users to send and receive tweets over SMS. The service uses Twilio's APIs, which were previously supported by O2 but have been dropped due to high costs. The developer has set up a Twitter app and deployed the application on Heroku, allowing users to access their personal Twitter account via SMS. The service includes features such as sending and receiving notifications of direct messages or @mentions from Twitter, making it useful for those who want to use Twitter without relying on data plans.