Gale is an open-source messaging system. It provides private messaging and public chat, uses strong end-to-end cryptography for security, and supports a distributed server network with a range of clients (both console and GUI) available. Gale is currently in early alpha testing. See the homepage for the details of its current status.
Keep in Touch aims to be a secure IM system for multiple platforms. It supports its own XML-based protocol as well as ICQ and AIM (toc). It provides encrypted connections between the server and client aswell as encrypted chat on all supported networks. The client can store contacts on the server allowing users to keep their contact lists between different locations.
SILC (Secure Internet Live Conferencing) is a protocol which provides secure conferencing services in the Internet. It can be used to send any kind of messages, in addition to normal text messages. This includes multimedia messages like images, video, and audio stream. All messages in the SILC network are encrypted and authenticated, and messages can also be digitally signed. SILC protocol supports AES, SHA-1, PKCS#1, PKCS#3, X.509, OpenPGP, and is being developed in the IETF. The software is delivered as SILC Client for end users, SILC Server for system administrators, and SILC Toolkit for application developers.