Definitely not ready for prime time, but it works with links now (see the example link in the video description). However, it probably wouldn't be very useful

Definitely not ready for prime time, but it works with links now (see the example link in the video description). However, it probably wouldn't be very useful for people in prison because it requires each party to have a dropbox account. Another project that might be relevant is miniLock, but it's still a ways away from being ready.