[techiferous]

This actually sets up a single point of failure for many apps. If a hacker were to hack rails.org, they could take down any site polling it.

[moe]

Well, not quite (when the messages are signed and the key is not stored on rails.org). However, as was pointed out, said attacker could indeed collect the ip-addresses of the polling servers - hence the idea to use twitter for the broadcast (a few comments down).

Of course Twitter is not exactly the most reliable platform but the likelihood of a twitter-downtime to coincide with a critical vulnerability seems relatively low.