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.
mxCrypto is an extension package that provides OO-style access to the cipher algorithms and hash functions included in OpenSSL/SSLeay, a very nifty cryptographic library originally written by Eric Young and now maintained by the OpenSSL team. Its main purpose is filling in the missing parts in Andrew Kuchling's pycrypt export package with high quality implementations. Due to the ITAR export restrictions on cryptographic software, Andrew's implementations are not legally downloadable from outside the US.