[yk]

No. Even if you could write a 'secure' RoR app, at some point the RoR framework becomes the weakest link. ( Or the Linux kernel, or the door of the datacenter.) And more general, security implies always a certain attack scenario, a strong password does not help against stolen hardware and a nuclear bunker does not help against a zero day. On the other hand, you can be quite secure against a plausible attacker, that is a attacker who is not willing to blow zero days against your personal blog. ( Or im general is not willing to spend a lot more than he can gain in the attack.)