GitHub User: jcasimir
Wow, so this is the best day of my OSS-writing life.
Kevin: Cells is a much bigger idea than Draper. Draper's decorators are forcing Ruby objects into the existing view layer. Cells are almost self-contained MVC systems.
JamesW: Models are about data and business logic, not presentation. In your example, deciding on the default avatar is a presentation issue, not really business logic. For XML or JSON it would be more logical to return an empty string from the default avatar, rather than referencing an irrelevant image.
Joel: I still need to work on the CanCan-compatibility, sorry I haven't had much OSS time lately. If Ryan has any suggestions I'll jump to implement them.