The MSNCP is a comprehensive client that operates on the MSN network.
The basic concept behind the MSNCP is to offer an easy and intuitive MMS client that can run on an ASCII console with a complete GUI. Sebastián Santisi is the sole author of this client, and the project is licensed under the GNU's GPL license. The msnlib has an OSL 2.0 license.
While the client is still in beta, it is definitely fully functional, and you can use it as an alternative to the Microsoft client. Although the client doesn't have all the features that the author thinks would make it complete, it is still a fantastic option you might want to consider.
Version 0.7.1 Beta: N/A