This would be fantastic:
http://blogs.zdnet.com/microsoft/?p=1420
4. Echoes will ensure text messages are delivered to Windows Live contacts as chat conversations, and replies will be sent back from Messenger as SMS
5. Voice calls can be connected through Echoes directly from the mobile to the Windows Live Messenger user’s PC
6. As the mobile user will appear always “online” to friends (using Echoes client emulation server), conversations also will be able to start from the Windows Live cloud, pushed to the mobile as SMS
…except I hate SMS.