In Agile, creating new ‘paths’ for feedback loops is KEY. Setting up software to help listen to your user base, Test Driven Development, Automated Builds, and Automated QA create metrics that helps get quicker, better, fine-grained feedback.
Google goes to great lengths to get feedback on the smallest of changes. They will post small color scheme and layout changes on their home page to a small subset of users and then gather metrics and statistics on the users behavior and compare it versus other layouts.
The difficult part is figuring out how you can ship SOMETHING to BETA every 3-6 months. How do you take that large application and convince management to deploy some small useful part of it. That’s the toughest part!