Just playing devil's advocate here: a truly evil attacker could use the access logs from all the apps phoning home to build a list of vulnerable targets! :)
Well, you are right, the idea wasn't thought out very well. I was in a bit of a bad mood during patching up various rails deployments around here...
However, perhaps they could just promise to post a signed message, in a specified format, on a dedicated twitter account, if such a thing happens again. This would seem like a relatively low-tech approach, about adequate for such a rare event (just keep that secret key secret!).
The community can then roll their own gems to watch said twitter-account and act according to any user preference. Perhaps one of these gems would even make it into rails-core after sufficient review.
Obviously one can always argue whether such a rare case deserves dedicated infrastructure. But on the other hand we have yet to see how many rails deployments will be bitten by this incident in the long term. It's not uncommon to see years of exploitation for a vulnerability in a popular piece of server software.
Your entire thread of comments here make me want to gouge my eyes out. A signed message on twitter? Low tech? What in the hell are you talking about?
I'm going to be the asshole here, because it is vitally important that no one responsible for security ever listen to what you're saying. You're advocating some Orwellian kill-switch mechanism based on unspecified "signed messages" over a third-party social messaging service (limited to 140 chars, no less), and throwing in meaningless phrases like "low tech". What about this problem leads you to believe we all need something low tech?
I am not qualified to design such a system. You are negatively qualified to even comment on such a system. Please stop.
Since you apparently neither understand what was discussed (an optional rather than an "Orwellian" kill-switch), nor the implementation options (a signed message via any broadcast mechanism), nor why using twitter as the transport would be feasible and "low-tech" versus most alternatives, you should perhaps refrain from commenting on this thread at all. - And especially not in that tone.
The aftermath of an incident like the current one is a lot more expensive than an unplanned downtime.