Just a few minutes ago Echofon and Tweetdeckannounced the availability of preview beta releases of their respective twitter clients featuring twitter’s new user stream API. The API essentially brings real time to twitter; no more refreshing required. When someone replies, retweets or favorites a tweet, you’ll see it all happen in your stream milliseconds after the person has done it.
It really has to be seen to be believed. If you were an avid Friendfeed user, this should bring back memories.