When creating an Enterprise layered architecture, I always find the discussion about To POCO or To DTO quite interesting. Each of these serve a specific purpose, however, there is a lot of confusions & misconceptions about differentiating between these. Stackoverflow, MS forum etc are full of questions about it. Adam Tuliper recently did a presentation for Techdays 2012 and he used a slide on same topic which provide comparison of these two in a nice way. Image below shows that particular slide. You can watch whole session here.
Until next, happy debugging.