From the Columbus Dispatch this morning:
There is always a domino effect. Ohio state law requires petitions for candidacy to be filed at least 90 days in advance of the March 6, 2012 primary (December 7, 2011), but both congressional and state legislative districts will have to have been drawn by then so candidates -- both incumbents and challengers -- know where they are running. This obviously puts a bit of pressure on state and local boards of elections to solidify the field of candidates and then print (or prepare electronic) ballots for the primary.
It remains to be seen if this news will actually filter down to members of the state legislature, some of whom may opt to introduce a bill that shifts the date on which the presidential primary (and those for other offices as well) is held. Though it didn't go anywhere, a group of Democratic state senators proposed a bill that would have moved the Ohio primary into January for the 2008 cycle. That would have been in violation of both national parties' delegate selection rules (And wouldn't it have been fun to tack Ohio onto the Florida/Michigan mess?). Of course, that didn't stop the bill's introduction.
File this one away and be on the lookout for other similar situations in other states where reapportionment has forced district redraws.