"You are right: The column view is not available anymore and also won't be available in later Dolphin releases. The decision to drop the column view was not easy. I myself liked the column view a lot and used it e.g. for browsing my music collection. However the column view has obviously been used by only very few people but was tricky and timeconsuming to maintain. For a project like Dolphin it is important that patches also can be written by non-core developers, but the column view introduced an internal code complexity that raised the "entry-barrier" for contributors unnecessary (and also made it tricky for us core-developers). In fact there is no big Dolphin team that can take care about maintaining something timeconsuming that is used by only a ratter small group (and I count myself as part of this group). So it was a hard decision but in the end we went for having a maintainable code-base to be able to do the things we offer really right instead of offering things that we are not able to maintain." - Peter Penz
http://ppenz.blogspot.com/2012/01/dolphin-20-status-update.html