I always recommend to teams newly transitioning to agile that they keep every iteration the same length. This helps them learn to manage their time, and after a few iterations they'll start to get a rhythm. Hopefully, they'll learn to work incrementally, doing testing and coding concurrently as part of one development effort, so that user stories are finished throughout the iteration, and testing isn't pushed to the last day.
Bob Aiello discusses how CM and agile practices can go hand in hand - provided that you have a solid framework to work with. With agile's popularity seemingly always on the rise, alongside the need for CM, learn how having both benefits everyone onboard.
For teams practicing Agile Software development, value working software over other artifacts, a feature from the release plan is not complete until you can demonstrate it to your customer, ideally in a shippable state. Agile teams strive to have a working system ("potentially shippable") ready at the end of each iteration. Release Management should be easy for an ideal agile team, as agile teams, in theory, are ready to release at regular intervals, and the release management aspect is the customer saying, "Ship it!."
Release Management is an awesome responsibility that plays a vital role in the success of a software development project. Releasing is often considered to be an activity that happens near the end of the process - a necessary evil perhaps, but no more.