Hi,
I live and work in OH. I got married in June 2007. My wife lived in NJ until Aug 2007 and moved from NJ to OH in Aug 2007. If I choose to file jointly for federal tax returns, do I need to file jointly for OH and NJ state returns? If I have a choice for the state returns, which one should I opt for - joint or separate?

It is your own choice.
If you file joint return, then on OH return you will report only the OH income
On NJ return, you will report only the NJ income.