Here are some links to documentation resources related to Telepathy.

APIs

• DBus API Spec
• Telepathy Glib API docs
• Telepathy Qt API docs
• Telepathy Farstream API docs

Reading Material

• Architectural overview
• Telepathy Developer's Manual (slightly outdated)
• Recipes: how to accomplish various tasks with the Telepathy API

Features

• Tubes
• Protocols Support
• Gabble XEP

Formats

• File Formats: specification for Telepathy's file formats
• service-profile-v1

Misc

• For developers interested in Telepathy within KDE, the KDE Community Project Page provides more information.