I recently installed 13.04 and successfully updated the whole OS. There was this friends app that came with Ubuntu to replace Gwibber, but now its gone and can't find it anywhere.
Unity has a social lens installed by default in Raring. While you can’t tweet from it you can view statuses, mentions, messages, etc.
Install Friends App (Gwibber rewritten in QML):
Ubuntu 13.04 Raring Ringtail: You can install Friends via command line:
sudo apt-get install friends-app