Thanks to Larney for the heads up
The MSN Messenger team have just released version 7.5 of the client to the masses.
Among the new features are Dymanic Backgrounds and Voice Clips. Dynamic Backgrounds fill your MSN Messenger conversations and subtly animate during the conversation. Voice Clips allow you to send short audio clips (15 secs max) to your friends on MSN Messenger.
New audio improvements mean talking over MSN Messenger is far improved from recent versions.
You can also do the following:
Start a conversation with a contact: msnim:chat?contact=
Add a contact to your contact list: msnim:add?contact=
Send an invitation to start a voice conversation: msnim:voice?contact=
Send an invitation to start a video conversation: msnim:video?contact=