My friend Peter has now published a first alpha version of his Linux filemanager codenamed "Dolphin". It is being implemented in C++, based on Qt. I know Peter's works from several years of joined efforts on a C++ framework, so I can really recommend Dolphin to Linux desktop users in KDE camp. Unlike Konqueror, Dolphin supports file operations exclusively and emphasizes on usability and performance.
Please give it a try, and tell Peter what you think about it.