Install iOS app directly from website - no password, no iTunes, no UDID

I just installed an app from a website - with no profile, no UDID, no anything. It just started installing. How is this possible? I am not jailbroken, not running the new beta 6. When it finished installing I tapped on it and it asked me if I was sure I wanted to run this app.

Link to app that installs 'silently'