If you want to add it to your sandbox, choose a menu command, click OK to a confirmation dialog, and it's done, cleanly, with no crap left around on your desktop. Informed participation with confirmation. That's how sandbox software will work. Fat Web Pages is a step in this direction. The first versions of Fat Pages were spec-less, a spec is there now.
Object types are now MIME types.
We use Base 64 encoding to pack the objects. The spec is wide open, I think, it should be possible for any database vendor to use it to distribute new parts. We made sure that the fat pages spec includes enough information so crawler scripts can visit a set of sites and get updated versions of already-installed software in a safe way. I believe the idea will find its way into the right places just by putting a pointer in this DaveNet piece. It's been an essential part of the process.