PeepCode on RSpec User Stories. The user stories look awesome as a replacement for Rails integration tests. The PeepCode is a good introduction on the topic, but falls awfully short on that issue. Using basic steps like saving an object, checking if it's valid and checking whether it was actually stored in the database is a little bit too simple in my book, and something you shouldn't be testing all that much anyway.

James Cox on Scaling Rails Apps.

The state of the Lambda in Ruby 1.9.

Living on the Edge (of Rails) #3 - X-Sendfile and many other sexy enhancements.

Howto: Write a Rails plug-in. In case you didn't already know.

Getting Code Ready for Ruby 1.9.

Zed Shaw on Audible Ajax. If his rant was too much for you, I'd recommend listening to this. It's a lot nicer to actually hear him talk about all these things.

Rubinius gets Multi-VM Support. Sweet!

Protecting custom SQL in Rails from SQL injections.