Apparently, the match between Anderson Silva and Ryo Chonan has been cancelled for the 12/31 Pride "Shockwave" card.
Several Japanese sites are reporting this to be so.
Zak Arnold at Puroresupower.com is reporting this as well. Zak mentions on his homepage that politics involving a Brazilian MMA faction may be the cause of the cancellation. He does not mention the name of the supposed Brazilian political power involved.
Could it be the Gracie's ? Remember, initially Chonan was rumored to be fighting Crosley Gracie on this card, and then just as quickly, Silva's name is mentioned as Chonan's opponent. Why ? Is Silva a better draw in Japan than Crosley ? Crosley looked pretty good in besting Mach Sakurai. So did Chonan for that matter.
If I had a choice, I'd opt for the Chonan / Silva fight myself.