I saw this free eBook title on Channel 9 while browsing the Webcasts. It certainly isn't anything ground breaking or revolutionary, but it is well put together and provides a refresher in a down to earth manner.
Sometimes in this field it's good to step back and look at what's going on from a different perspective. This eBook does exactly that by discussing Domain Driven Development in comparison with the Data Driven Development we've become accustomed to with .Net. The author doesn't dismiss the data driven approach, but in fact shows that in some cases it may be the right choice. At the same time he does a great job introducing Domain Driven Development in practical way by example.