I'm able to play a track faster or slower as in real. But is it possible to make this dynamic? that the clip is getting faster and faster after each second? or slower and slower till completly stop? i hope you understand what i mean...

sorry for my worse english :)

Yes, I'd also love to see some ramped slo-mo :)

http://www.kdenlive.org/mantis/view.php?id=1026

This is actually not as easy as it sounds. Especially for slow motion (you need optical flow estimation for this to interpolate between frames and avoid jerky videos). So I would not expect this to arrive too soon.

Thats a general question.... I also wonder is there a possibility to dynamically change any parameter of the effect? This concerns not only speed but transparency or zoom...

Not yet. Just linear transitions (e.g. the keyframable Volume effect).