I have a straight barbed wire and I want it to look more like this:
http://www1.istockphoto.com/file_thumbview_approve/297873/2/istockphoto_297873_barbed_wire_fence.jpg
It is possible to take every node manually, but it takes a long time and it doesnt look good.
I have 0.45 (0.46 was filled with bugs. at least the program crashed several times)

If I remember correctly there was an effect in 0.45 you can use, I think it was called Pattern along path (search for it in Effects). You have to draw a curvy path, that will be the "skeleton" for your barbwire. Select them both and run the effect.

0.46 will be out very soon and Live path effects are a huge step forward for things like this.

Thanks