Now Drupal 4.7.0 is released, people start clamoring for some kind of roadmap. Drupal never had an official roadmap, and will never have one. People perceive a roadmap as a list of formal deliverables; they feel stranded when the roadmap is changed, and get upset when functionality is not completed in time. Volunteer-driven projects like Drupal can't make any guarantees. Things happen, or not. Code is ready, when it's ready. Volunteer-driven projects don't mix well with official roadmaps.
As the Drupal community grows, those who disagree with not having an official roadmap have become increasingly articulate.
Of course, I recognize that it is necessary for people to have some idea of where Drupal is heading. It enhances good communication and creates synergy between developers. Hoping that some people will engage in the opportunities, and that we can collaborate effectively, I'll start talking more about the directions Drupal is heading in, some of the decisions that are made, and the functionality I'd like to see integrated into Drupal core.
At the end of the day, it's all about better communication.
— Dries Buytaert