I have been planning to develop a localized messenger service for Bangladeshi peoples for quite a long time. I studied a lot on this topic and many times attempted to kick start the development, but unfortunately I ran out of time every time. But what I found is a wide range of libraries available for developers to develop such a service without spending a great amount of time. Let me list some of them here for You

1. Wildfire IM Server with IM Gateway [Java]
2. sendMsg [PHP For MSN (The Best)]
3. MSNP [PHP for MSN]
4. Joscar [Java for AOL/ICQ]
5. jYMSG[Java For YM]
6. TjMSNLib [Java for MSN]
7. Java-Jml [Java for MSN]

Are you interested????