The Drupal Zen sub-theme, Zen Classic, is to no longer be included with the Zen theme download. The Zen theme will now purely be a theme framework and starter kit. If the Zen Classic theme is to be continued it may be done so as a separate project. Although many people said it was bland I quite liked the simplicity of it, but since it’s been removed and I’ve been thinking of redesigning my site anyway maybe this was the kick up the butt I needed to put pencil to paper!
In terms of Zen sub-themes there are a few available to download from the Drupal website: http://drupal.org/node/340837
There’s also a list of sites implementing Zen over at: http://groups.drupal.org/taxonomy/term/5171