I was introduced to Ruby for the first time at Codemash 2010. The purpose of the session was to get introduced to Ruby syntax and have a solid base to grow from. The method used Ruby Koans from EdgeCase. You can get the files and read an explanation of koans on Github.
Basically, koans are a series of failing tests that you have to fix in order to move forward. As you fix each test in a file, you run the file in a terminal window to see the results. If you fixed the test correctly, it will move on to the next error. The point is not to move through the test as quickly as you can, but to stop and understand each test as you go. First, why is it broken, second, fix it, third, improve it (Red, Green, Refactor). Every time you solve a test, go back to make sure you understand what you actually fixed and why it works. The koans each build upon each other and upon your knowledge of Ruby as you gain it.
If you have ever been interested in learning Ruby, koans are definitely a great way to get acquainted with the language!