As I mentioned yesterday, the Mets are changing the Citi Field center field wall for 2010. From the descriptions in the articles, I think this is what it will look like. I don't think it was done to get more home runs, more just to make the wall fairer. Really, the only point of having the wall jump to 16 feet in dead center field was to create a batter's eye to block the apple. No reason to have the HR line that high.
I don't recall too many balls hitting the wall that far out in 2009, so I don't think it will affect play much in 2010.