Details about the Fedor Emelianenko vs. Dan Henderson superfight are emerging as I type this. According to Jonathan Snowden, the parties behind the two fighters have found a mutually-agreed upon weight. Here's his Tweet:
Sources close to the promotion say the Fedor-Henderson fight will at a catchweight of 220. It will be promoted as a heavyweight bout.less than a minute ago via web 
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Jonathan Snowden
mmaencyclopedia
This makes sense for the parties involved. Henderson performs his best at light heavyweight, not middleweight. Even when he cuts to make 205lbs, he likely rehydrates to 215lbs or more the following day. The bottomline is this: Henderson can make 220lbs effortlessly.
A 220lbs limit will force Emelianenko to make a slight adjustment in weight, notably a loss of approximately 10lbs. While I suspect this will come from a changed diet and not a water weight cut, it arguably benefits the Russian regardless. Emelianenko will need his speed to compete against the naturally smaller Henderson and a regimented reduction of 10lbs provides the Russian that important performance boost.
More on this story as it develops.