theme7

theme7 is a very small utility module providing theme7() function as a wrapper for core theme() function, with the only difference being that it accepts all theme hook arguments as an associative array of variables (like in Drupal 7) instead of list of arguments (standard way in Drupal 6).

Which essentially means that instead of using for example:

theme('table', $header, $rows);

you can now use:

theme7('table', array('header' => $header, 'rows' => $rows));

Using this means that the way of providing theme hook arguments could stay the same between D6 and D7 versions of the same module (with only a slight difference in the function name). Also there is no need to worry anymore about the order of the arguments in an array, as this dealt with automatically by theme7() wrapper based on Drupal's theme registry.