While WPF4 does support multi-touch, it does not have any built in gesture support, at least not of the kind you are thinking about. Features such as flick, pinch-zoom, etc. all have to be programmed on top of WPF4.
I don't know of any higher-level gesture support toolkits but writing your own is not as hard as it sounds. This WPF4 touch sample shows for example touch based move, pinch-zoom and pinch-rotate:
If you compile and run the sample you'll see the handlers are only ten to twenty lines of code and make use of powerful infrastructure in the touch API itself and core WPF features such as transformation matrices. The touch API supports inertia, etc. so try your hand at a flick that meets your needs.
Also, of course, this sample only works with Pen and Touch input devices, not an ordinary mouse, but you specified that your are developing a touch application.
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