In the scene(s) in Batman Begins where Bruce is setting up the Batcave and testing various components of the Batsuit and the devices/weapons he would use, there is a scene where he has what looks like long spars or claws from the fingers of gloves he is wearing.
He was able to stretch them taut, then let them sag by the flick of a wrist. What was that? We don't see it later in the film that I could see. Was it a precursor to one of the devices he uses in the later films?
I'm going off a fairly faint memory here, but I think that those "straps" were to be the membranes of his cape. Lucius Fox showed him earlier the special cloth that when given an electric charge would go rigid.
Bruce was practicing making the cloth go rigid using the gloves to trigger it. This allows him to force the cape to a particular shape, allowing him to glide short distances (I think this was used to great effect in The Dark Knight where he base jumps from a different building to pick up the money launderer while in Japan/Hong Kong).
Here is the scene where Fox demonstrates the material:
(The scene in the question can be view at the 3:10 mark of the same video.)
