I ran into the same problem as bangpound when I wanted to downgrade from PHP 5.3 on MacPorts to Drupal 6. Although Drupal 6.14 supports PHP 5, when I set up a new install, install.php became a sea of "function ereg() is deprecated."

I don't have Macports in SVN and instead just do "sudo port install ." I was able to switch back to PHP 5.2.11 with the following:

1. sudo port deactivate php5
2. sudo port install php52 +mysql5 (this probably wasn't available when he wrote the initial blog post)

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"