There has been some talk about it.
DCM staffer John C comments in this post: "As for the Spirit, nobody has yet to find any copyrights on the material. If you think we should be looking somewhere else, though, rather than the usual, "Eisner was a good businessman so he must have secured copyrights" hypothesis, we'll be glad to investigate."
BTW, you link goes to an Asian website.
-Yoc