I went through the A3 and A4 without many problems. My only early problem was that I was on a plane and couldn't download the css and images needed for Iteration A4. When it came time for Playtime, I got a little stuck on the second question, "Change the error message associated with one of your validations." I was trying to change the error messages for multiple fields with one :message. I finally figured out that I needed to define unique messages for each field like this.

Now I'm testing blogging from TextMate.

validates_uniqueness_of :title, :message => "must be unique"