Since I noticed that the gradients (. Grr) stored in 'special folder of Gimp you can carry on items ritrovarselo, I wondered if it was possible to save and load all the gradients along the opening to choose them and not to redo the work ( even those of Gimp that I already so with the samples)? if not now in future versions had thought?

As of version 0.46, it's not possible to save gradients. v0.47 is due out very soon, and 0.47 pre4 is already available. However, I don't know if saving gradients is possible in this most current version. You might check this website for details and future plans etc.
http://inkscape.org/ (Check out Roadmap link )

If I'm not mistaken, it is possible to use GIMP gradients in Inkscape. Although I have to admit that I don't remember exactly how to do it.

I wish I could be of more help, but you should be able to find answers at the link above.
All best

Not sure of this is what your are referring too, but when I create gradients that I want to use over and over in Inkscape I do this two part process described in this thread. Then when I want use the gradient I just drag and drop the file into whatever I am working with and the gradient shows up just fine.