Site builders that need the smiley panel *now* may move away to the Guestbook fork unless there are good reasons not to... But that is another issue.

Smileys has hardcoded integration for node and comment forms. Drupal Guestbook Smileys enables the smileys panel for Drupal Guestbook. There are issues in the Smileys project requesting to fix this in the Smileys project, but not nothing yet.
#257962: How to add smiley panel to guestbook
#305949: Need for the smileys module to work with the guestbook on drupal 6
#302738: How to attach smilies on Guestbook page?

What is the direction for this project? The dgb_smileys.module is small and the approach is easy enough to evaluate. What do you think?