Quoting Earl Miles <merlin@logrus.com>:
2) You will be unable to offer the people who do use your modules and are likely to demand features those features. Yes, you can say you've built them...and now they must wait until Drupal 6 is available and usable. Remember, the people who actually *use* Drupal (i.e, for real production purposes) are strongly encouraged not to use a version of Drupal until it is ready and stable. At our current plan, with a Jun 1 code freeze, chances are Drupal 6 will be out sometime in the fall. That means anyone doing new features for modules exclusively in HEAD *right now* will experience greater than half a year lag of those features being available to those features being actively used.
Forgive my ignorance in the matter but aren't there two HEAD modules; drupal and contributions? Doesn't a HEAD freeze only affect the drupal module? It seems to me that the contributed modules control their own destiny in this matter. Earnie