There was a discussion a while back where Adrian proposed using
array data to abstract the database creation.
Each column and its attributes (number, text, ...etc.) will become
like FormAPI is today.
This removes the overhead of maintaining two (or more) separate
schemas in the install.
Here is the discussion
http://lists.drupal.org/archives/development/2006-05/msg00456.html
Here is the issue for it
http://drupal.org/node/63049