http://www.dot.state.oh.us/districts/D02/Pages/Diverging-Diamond-in-Perrysburg.aspx
The OH 25 / I-475 interchange in Perrysburg will be converted to a diverging diamond starting in 2016. Unless I'm missing something, this will be the second DDI in Ohio.
I don't know which will be done first, but there's one thats been approved (http://www.athensnews.com/news/local/e-state-u-s-interchange-plan-selected/article_aee6d0fc-4d08-561b-8bb4-4de5cd9e1a60.html) in Athens as well.
Ha, figured that would happen when I titled this thread. That article says the Athens one will also start in 2016, so I guess either one could end up being Ohio's 2nd DDI (unless there's yet another one I'm missing)