From the Bengals' PR department:

While the NFL has recognized the legal name change of Chad Johnson to Chad Ocho Cinco, the league informed the Bengals today that certain issues remain to be resolved before Ocho Cinco will be permitted to wear his new surname on his jersey.

He will wear the name Johnson on his jersey today and will be referred to as Chad Johnson on the official play-by-play sheet.

Further questions should be directed to the league office.