I really like the system MC employs--showing the Display window, tagging info, action window, etc. on the left side of the player in a nice, gentle window which doesn't require a popup.
What if more than one window could be open at once? I really think you could further the usefulness of this feature and set it up like the DSP studio where the user would have checkboxes for items to display. I surely would want Tags, Display, Action Window, and possibly one more based on the task at hand--and I have the realestate to display them. At 1200 pixels tall, the current window and top text + podcast list looks like I could easily fit 3 more boxes approximately the same size of the tags window.
Please add another item under podcasts called Downloading Podcasts. I don't like having to run through each item if I want to see if anything needs to be downloaded. It could be the same color as Downloaded Podcasts.