Thanks for the overwhelming response - making the front page of HackerNews unexpectedly. DeployButton was our entry to RailsRumble this year, and it's a solution we created because we wanted something like this for ourselves for our own startup, Lizi.
Over the next few weeks, we'll be updating a few key issues that have been raised in these comments, including the ones about security.
We don't immediately accept that enterprises will jump to use DeployButton, but for a series of smaller consultancies, the security features we will offer will be more than enough.
Thanks again for the support - Sometimes I wish there was a "Whoops, we're not ready for HackerNews yet, don't taze me bro" break-the-glass button that puts us back on after a month's time.