The Live Framework is the API for Live Mesh. Since the PDC last year you could register for the Live Framework key to download the SDK.
With the new update you have now public access to the SDK & Visual Studio Tools:
Update: You need an Live Framework Token to run an application :/
I found a small article on ZDNet how a Live Mesh application might look like. There is a link to a simple "Live Mesh styled" "ToDo" App.
The SDK, a new Live Mesh release and so on should we see at the PDC 
The "Live Mesh" was anounced on the Mix08 – a few days ago the closed beta started and Microsoft give some more information about it:
The architecture (from the videos above) :
German
English
