Kim is a Kde Image Menu. It has a ton of handy features for images. Only the flash slideshow in kde4 doesn't work(taken from the repos).
Kim_gallery looks in the directory /usr/share/kim/, while the new(kde4) directory for kim is /usr/share/apps/kim/.
To solve this problem, open /usr/bin/kim_gallery as root with kwrite(or another text editor), and change the line "KIM_DIR=$kdeinstdir/share/kim/slideshow" to "KIM_DIR=$kdeinstdir/share/apps/kim/slideshow".
Save it, and try again. It should create a fine flash slideshow of your photos.
Maybe this error could be fixed when kim will be upgraded in the repos?