After my presentation at the Nashville PMI IT Local Interest Group last night, several project managers stayed to talk about estimating and project forecasting with Scrum. One was skeptical about being able to reliably tell management where they would be 6 months or 1 year down the road. Another was in an experienced XP shop that only planned for the current iteration and was having trouble meeting long term goals. The coincided with a thread on the Lean/Agile Yahoo group about estimation and planning that includes contributions from many experienced Agile leaders.
One of the posts had a link to an older presentation by Mike Cohn at Google on estimating that is a fantastic introduction to how to estimate and forecast in an Agile project. Here is the PDF version and the YouTube part 1 and 2 are below. He has many of the examples I have seen and used in my presentations based on studies done at Simula Research Laboratories in Norway. It is good to have this research for the skeptics you will eventually encounter. I really like the "Zoo Points" exercise and plan to add it to my training. Mike (and others) have many more great presentations at the Mountain Goat Software site.
This is a great intro to estimating User Stories (i.e. Product Backlog Items) and performing release planning to have an idea of where your project might be far into the future.