Ubuntu ships by default Gwibber, a powerful social client, that allows users to use Twitter, Identi.ca, Facebook, etc, from one global interface, furthermore, adding a dedicated lens (available via Ubuntu Software Center, available by default starting with Ubuntu 12.10).
Nevertheless, various users, across the internets, are stating that, while Gwibber features a pleasant-to-the-eye interface and wide support for numerous services, lacks speed and fluidity, especially on scrolling through its displayed contacts.