This bout, a rematch, has been talked about for years. Hopkins would never accept a fight with Roy where Roy got 50% of the cut. Roy has really gone after Hopkins this year and was even willing to accept a winner take all scenario but Hopkins wouldn't bite. Apparently that has been ironed out now. See the link at end of post.
After seeing their recent performances and looking at their styles, I think Roy will win a decision. Much like he did back in 1993.
Here's a great article explaining the money and the method for deciding who walks out first, etc.:
Roy Jones, Bernard Hopkins to fight in 2010 - ESPN