Dolphin for KDE 4.3 will have some improvements for the Information Panel. One improvement is that Nepomuk is used to get the meta data, which allows to show a lot more information:
Currently the meta data titles are internal names used by Nepomuk (e. g. "audioCodec"), but this (hopefully) will be improved until KDE 4.3 so that it is written as "Audio Codec:".
It is also possible now to configure which informations should be shown:
Because of Phonon it is possible to play audio files:
... or even videos:
Please note that it is not the intention to convert Dolphin into an audio-player or video-player. The current functionality is just meant as improved preview for media files.
Final remark: Until KDE 4.2 it was possible that Dolphin got blocked for several seconds when reading the meta data of specific files (huge videos, compressed files). The nice thing about using Nepomuk is that no blocking occurs anymore, as the meta data parsing has been done already outside the context of Dolphin.