This is why I fix the versions on ALL my gems to a known good version. Updates can only happen by changing that version in my source. Tests will be run after that, of course. I'm pretty sure it's standard practice now, but I can't believe there was a time when I didn't do this.

Just 2 days ago, a new version of authlogic was released that accidentally broke 2.3.5 compatibility. And that's a respected and widely used gem. It happens. Also, many gems are starting to deliberately break rals 2.3 compatibility - their newer versions are rails 3 only. Not to mention that gem authors sometimes deprecate and then obsolete some interfaces. So if you're not fixing your versions yet, and you don't have "sane practices" for updating them, it's time to start.