I can't tell if this is a documentation bug, or a missing folder :)
The Drupal-port-README.txt says,
The folder heirarchy is changed to suit Drupal. Each styles show up as different themes on Drupal theme administration page.
The style.css says,
@import url('sandbox-threecolumn-both/style.css');
So, I'm thinking there's supposed to be a folder for each of the default Sandbox styles. But ...
azumi:~/Sites/drupal/sites/all/modules chris$ tar -tzvf ~/Documents/src/Drupal/themes/sandbox-theme-5.x-0.x-dev.tar.gz
drwxr-sr-x drupal-cron/drupal-cron 0 2007-07-01 12:12 sandbox-theme/
-rw-r--r-- drupal-cron/drupal-cron 14940 2006-04-23 21:54 sandbox-theme/LICENSE.txt
-rw-r--r-- drupal-cron/drupal-cron 46 2007-06-27 02:41 sandbox-theme/COPYING.txt
-rw-r--r-- drupal-cron/drupal-cron 151 2007-06-27 02:41 sandbox-theme/Drupal-port-README.txt
-rw-r--r-- drupal-cron/drupal-cron 437 2007-06-27 02:41 sandbox-theme/README.txt
-rw-r--r-- drupal-cron/drupal-cron 261 2007-06-27 02:41 sandbox-theme/block.tpl.php
-rw-r--r-- drupal-cron/drupal-cron 167 2007-06-27 02:41 sandbox-theme/box.tpl.php
-rw-r--r-- drupal-cron/drupal-cron 500 2007-06-27 02:41 sandbox-theme/comment.tpl.php
-rw-r--r-- drupal-cron/drupal-cron 218 2007-06-27 02:41 sandbox-theme/layouts-readme.txt
-rw-r--r-- drupal-cron/drupal-cron 612 2007-06-27 02:41 sandbox-theme/node.tpl.php
-rw-r--r-- drupal-cron/drupal-cron 2475 2007-06-30 17:57 sandbox-theme/page.tpl.php
-rw-r--r-- drupal-cron/drupal-cron 33835 2007-06-27 02:41 sandbox-theme/readme.html
-rw-r--r-- drupal-cron/drupal-cron 27423 2007-06-28 03:49 sandbox-theme/screenshot-large.png
-rw-r--r-- drupal-cron/drupal-cron 10595 2007-06-27 02:41 sandbox-theme/screenshot.png
-rw-r--r-- drupal-cron/drupal-cron 2710 2007-07-01 08:04 sandbox-theme/style.css
There ain't, not in the one I downloaded anyhow.
Is there another file I should get?
On the other hand, it's super-plaintxt now :)