If your team/organization has taken on and sustained the practice of project retrospectives (see my earlier post), I applaud you. Great initial step, but you're not going to see the true value from this practice without going further. You're now faced with the opportunity not only to reflect and maybe get some clarity on the bigger picture successes and challenges, but also to memorialize those so others can actually do something with that information.
All of those lessons learned around capturing what propelled and confronting what dragged will forever be buried in those notes/outputs unless they are actually shared, understood, and considered next time around by other teams.
I'll repeat: Lessons learned die in PowerPoint decks… unless shared, understood, and considered next time around.
Arguably, there is a responsibility to generally socialize these lessons learned across other teams and beyond within your organization so some things actually start to take hold. These things can span what might need to be integrated into the way everyone approaches a plan, how they kick off a project, or how similar challenges are handled at any point by anyone who encounters them.
This is true Knowledge Management at work, and as with any KM paradigm set up for success, will only be effective by combining the right tools, processes, and people responsible for sustaining this continuous improvement paradigm.