Some great news out of the KDE 4 development: Dolphin will replace/coexist with Konqueror as the main file manager. One of my few issues with KDE is Konqueror -- trying to be both a web browser and a file manager, when it really is more a web browser. All the options are basically exclusively oriented toward web browsing and its incredibly convoluted "Profile" system. Its truly indicative of feature creep.
Dolphin is my primary file manager, however its not truly integrated with the rest of KDE-- more of a standalone application. Giving users the option of an integrated and dedicated file manager is exactly what KDE has been missing. I'm impressed they are shooting for a summer '07 release. Looks like Fiesty+1 is shaping up to be quite a release.