Feedback is very important in tuning software development, but it's also needed in tuning the software development process. It comes in two major forms, introspection and retrospectives. Both involve looking back at what you've done, what went right, what could be improved, but introspection is solo and retrospectives involve the team.
Singing the Songs of Project Experience: Patterns and Retrospectives by Linda Rising and Esther Derby from [http://www.estherderby.com/articles/rising-derby.pdf Cutter IT Journal] (PDF)
Restrospective Agility by Tim Mackinnon in [http://www.ratio.co.uk/ov8pdf.pdf Objective View] (PDF)