Test-driven development is one of the best benefits that Ruby on Rails brings to modern web development, but it can be a bit tricky, and laborious, constantly tweaking test code, running the tests, then making required changes. Enter autotest, part of a suite called ZenTest, which makes life dramatically easier for you.
Here's an easy way to keep track of the on-going changes to Ruby on Rails. The Rails team use the system Trac to manage their development and it includes a page to list all of the recent changes. While nice in theory, the fact that by default it shows changes to the development website too makes it a little confusing at first glance, so instead you can use/bookmark this link to see what is going on in the code itself:
Just a quick mention that Ruby on Railsversion 1.1 has just been released, adding some really awesome new features that will continue to make life even easier for web developers everywhere, yes, including even you.