I installed Ruby 1.9.2 on OS X Lion using brew install ruby and updated gem to 1.8.11 using gem update --system.
However, on my Rails 3 project, bundle is still using the Ruby 1.8 path (/System/Library/Frameworks/Ruby.framework/Versions/1.8/Ruby) to install new gems and fails with packages that require Ruby 1.9 (linecache19 in my case).
How do I let bundle know that I installed 1.9.2?
(I tried using RVM to installed Ruby and failed for some reason. The installer simply hand. I think the network connection was too slow or something)
I retried rvm and it now it works like a charm. Apparently, this is the way to go.