Channel9 posted an interesting video looking behind the scenes at the Live Mesh peer-to-peer synch. Its 30mins long but if you’ve got the time to kill its worth watching. Some of the topics covered (in order) are:

• The 5GB quota for storing files in the cloud and how users can still synch files between devices when this limit is exceeded
• How Mesh uses the feed and enclosure service to synchronise files between clients, and how Microsoft plans to make this process more balanced in the future to stop multiple devices trying to download the same file from just one client.
• Ghosting, where users want to synchronise files between clients but not upload to the cloud. Currently this isn’t exposed in the UI but it is built into the service. For example when exceeding the 5GB limit mentioned above.
• Performance enhancements. How the Mesh team is looking to increase the intelligence of client downloads, both through downloading chunks and differentials and through using non-busy machines to serve the files.
• How they’ve used technologies in Messenger voice + video to get through firewalls
• How using the Mesh API, developers will be able to make an application connect across the mesh network using peer to peer synch, and also extending this to Windows and other Microsoft applications. (Messenger is one they mention.)

David Steere and Trevor Robinson: How Live Mesh P2P Syncing Works