This module will not be developed for Drupal 7, as the functionality is now in Drupal core.
The teaser by content type module allows an admin to set a different teaser length for each content type. Note that as with the site-wide setting, this only affects new posts or new edits of posts.
Teaser length is set on the individual content type settings pages. Choose 'Default' to use the original site-wide setting for teaser length.
To regenerate all teasers for your site, install the retease module.