Dropbox to add "LAN sync"

From an email today:

In addition to the iPhone app, we're also finishing up a new version of the Dropbox desktop software that features numerous performance improvements and our new "LAN sync" feature. LAN sync knows when Dropboxes are on the same network and will automatically exchange files directly between computers instead of downloading them from our servers - this makes sharing large files in an office environment much faster than was previously possible.

I hope there's an option to keep some files off the server, as well. Would be nice to be able to use Dropbox for everything!