What is this Live Mesh and why do I care as a developer?

Well, I am not going to try to answer that:).  No seriously, the best way to get this question answered is to watch a MUST SEE video on Channel 9 called Programming the Mesh.  One of the many scenarios I think you'll find interesting is using Live Mesh to bring a web based Silverlight application into the Mesh and make it available out of browser and enable offline use of the app.  Let me say that again, OUT OF BROWSER AND OFFLINE!  The demo is about 27 minutes into the video, but I wouldn't skip forward because then you'll miss the fundamentals which help you understand how it and the other demos work.  The Mesh opens up many interesting scenarios.  Why are you still reading this?  Go check out the video!