Ist zum Glück nicht wegoptimiert:
http://ppenz.blogspot.com/2012/01/dolphin-20-status-update.html?showComment=1325712810688#c2524689078457646051

> Last time I've tried 4.8 snapshot,
> dolphin didn't support inline
> renaming, was this dropped?

It has not been dropped, but I could not integrate it in time into the view-engine for Dolphin 2.0. So it has been temporary disabled and inline-renaming will be back again in 2.1 (see http://community.kde.org/Dolphin/Dolphin-2.0-Status for details).