The Scigraphica is really nice thing!
I was looking for something like that for quite a long time.
The lack of origin(sigmaplot, kaleidagraph) like programs under linux is real pain for a lot of people(I belive). Now we have hope to get nice thing to work with.
By the way, where I can post my suggestions about sga?
I have got some already!
You can post them to the scigraphica mailing list