Twitterfeed will soon support PubSubHubbub.

PubSubHubbub is a simple, open-source, server-to-server RSS subscription and publishing protocol extension that helps publishers instantly push new articles to supported RSS readers when new content is posted. Twitterfeed is currently the most popular RSS tracking and distribution service on the Twitter platform. Users can add RSS feed URLs they wish to follow to the Twitterfeed service, and when there are new articles from that feed, they will automatically be pushed to the user's Twitter account, saving the hassle of manual operations in the future. Recently, Twitterfeed announced that it will add support for PubSubHubbub, allowing RSS feed URLs added via Twitterfeed to be updated in real-time and pushed to Twitter.