Focused Freshmen-an oxymoron?

If someone had told me two years ago that it was possible for my freshmen to work in self-directed teams and be productive and only a handful would be off-task, I'd have laughed in disbelief. That was the case this Friday in our English/World History classroom. I didn't think much of it as our students worked with each other, dividing tasks among their teams, researching with the internet, textbooks, and other print resources. It was only that evening when I compared this group-work experience to any other project I'd tried in my traditional classroom that I realized how far we have come.
Looking back to our PBLs in September, I remember that our students needed us much more (to help brainstorm, divide the responsibilities, keep them focused, research, and coach them along with their final products). Although we still have to re-direct a handful of them to focus on the task at hand, our roles are evolving to less of the "micro-managing" and more to challenging them to go further with their ideas through questioning.
How did we get here? Through their previous team-work experiences, I think our students have learned that they will be held accountable for their work and that they will not be given extra time when they didn't use class time efficiently. It took those prior experiences, many of which weren't pretty and make me cringe to think about, to get them to this more focused and independent level.
Now the question is what do we focus on improving next?