I've once asked about this from Klaus and he did not see this feasible at that time. If I remember correctly he thought that this would be something that should be done in the device itself.
 
Well I was just watching a DVD with PowerDVD windows player and it has the ability to play back with 1.5x and 2.0x speeds with sound. Without changing the pitch. And that has to be done with software since I have no kind of hardware to do that. I know that mplayer can play with many speeds with sound but the pitch changes also.
 
So I am not sure in which direction this feature request should be aimed at :)
 
Originally I had this idea from my JVC hd recorder which has 1.5x playback possibility. Sometimes there are programs that you just wand to speed up a little :D
 
Oh, and ofcourse subtitling should work also as it does with PowerDVD.
 
BR
Kartsa