Connection Managers
Connection Managers are the components responsible for actually connecting to the Jabber/AIM/... server. Your distribution probably has packages for most or all of the current CMs, so you don't need to install from source unless you're on a weird distro or want to hack on them.
Stable
Gabble: A Jabber/XMPP connection manager that handles single- and multi-user chats and voice/video calls.
git clone git://git.collabora.co.uk/git/telepathy-gabble.git
Salut: A link-local XMPP connection manager (XEP-0174). CategorySalut
git clone git://git.collabora.co.uk/git/telepathy-salut.git
Idle: A IRC connection manager.
git clone git://git.collabora.co.uk/git/telepathy-idle.git
Telepathy-SofiaSIP: A SIP connection manager based around the Sofia-SIP library.
git clone git://git.collabora.co.uk/git/telepathy-sofiasip.git
Releases (source code); older releases can be found on the SF.net project page.
Under Development
Haze: A connection manager based on Pidgin's libpurple, supporting all protocols in Pidgin (AIM, ICQ, Yahoo, MSN, etc) at a basic level, but already very usable.
Releases (source code); new releases are announced on the Telepathy mailing list.
git clone git://git.collabora.co.uk/git/telepathy-haze.git
Requires libpurple and Telepathy GLib
Butterfly: An MSN connection manager that handles presence, conversations, avatars, personal messages, server-side aliases, and full contact management (including groups).
git clone git://git.collabora.co.uk/git/telepathy-butterfly.git
Requires pymsn and Telepathy Python.
Dead
Wilde: An AOL/ICQ (Oscar) connection manager, this handles single direct messaging, presence, conversations and simple buddy list (add/remove).
Clients
As a user, you interact with a Telepathy Client.
Empathy: a Gnome IM/voice/video client reusing Gossip's UI and using Nokia's Mission Control
The instant messaging, address book and VoIP user interfaces on Nokia's Maemo-powered internet tablets (such as the N800 and N810) are Telepathy clients.
Dead?
Ereseva: VOIP-capable webphone, based on tapioca-python and GTK+ libraries. (Ereseva SVN repository)
Landell: a GNOME Instant Messenger built around Tapioca# (C#/Mono)
Cohoba: a UI for GNOME desktops by Raphaël Slinckx (Python)
GnomeUI: an experimental UI for Gnome desktops by Adam Lofts (C#/Mono)
Banter: a Gnome IM/voice/video client with a rich user interface (C#/Mono)
Tools
Telepathy Inspector: A telepathy client (GTK+) whose objective is to expose all interfaces and functionalities implemented by a given connection manager along with its connections, channels, etc.
Libraries
Telepathy GLib: A GLib/GObject-based library for clients and connection managers
Telepathy-Qt4: Qt4 library for use in Telepathy clients, including a Qt binding for Telepathy-Farsight
Telepathy Python: Python libraries for use in Telepathy clients (e.g. Cohoba) and connection managers (e.g. Butterfly)
Telepathy-Farsight: a GLib/GObject library that uses Farsight and GStreamer to handle media streaming for channels with the MediaSignalling interface
Older libraries
These libraries are not up to date with current versions of telepathy-spec.
TelepathySharp: A .NET library for use in Telepathy clients
TapiocaSharp: A high-level .NET library on top of TelepathySharp for use in Telepathy clients (e.g. landell)
TelepathyQt: Older Qt4 libraries for use in Telepathy clients and connection managers
TapiocaQt: A high-level Qt4 library on top of TelepathyQt for use in Telepathy clients (e.g. decibel, kopete)
libtelepathy: A GLib library to ease writing Telepathy clients in glib; deprecated in favour of Telepathy GLib. releases
Other Components
Mission Control: an Account Manager and Channel Dispatcher implementation, which stores accounts and coordinates the launching of connection managers and clients.
Stream engine: A Telepathy client that uses Farsight and GStreamer to handle media streaming for channels with the MediaSignalling interface; mostly deprecated in favour of Telepathy-Farsight. releases
telepathy-feed: A Galago feed for Telepathy. http://telepathy.freedesktop.org/releases/telepathy-feed
2006 Summer of Code projects
Antoine Perdaens is working on a OSCAR protocol implementation, adding Audio and Video presence and conferencing negotiation - OscarSOC