While at Agile 2008, I had the pleasure of speaking with Bob Payne on the subject of Agile Portfolio Management (amongst other topics).
Listen to the podcast here: https://agiletoolkit.libsyn.com/index.php?post_id=369243.
Also, make sure you check out the Agile PMO Blog post: https://lithespeed.blogspot.com/2008/07/introducing-lean-agile-pmo.html.