We often hear people say “We’re agile, we don’t need a plan” or even worse “We can’t plan”. This is just not true. Release Planning in agile is as important as it is in traditional projects, the only difference is there are a few techniques that help make sure the plans bear some relation to reality. We’ve all worked on projects where you know from day one that you will be late, and yet no one does anything about it. Agile planning is different. We give up the illusion of control of traditional rigid plans, and replace it with a clear view of where we actually are, even if it’s badly behind schedule, so that we can make decisions based on what is actually possible.
Source: A Coach’s Guide to Release Planning, Samantha Laing and Karen Greaves, http://leanpub.com/ReleasePlanning