Rails 3.0.20 was released Jan 28 and includes another critical security fix for yaml -> json vulnerabilities. I sent a pull request for BibApp/master after applying it to our production BibApp.
The only trouble I had when updating was Bundler not finding the correct activesupport gem, this happened on my development machine too, but maybe for different reasons. After removing and reinstalling the gem - and, in production, making sure I started Passenger with the correct Ruby :/ - then everything was good.
Jason