Update (3:38 p.m. EDT): A bit more coverage worth your click: Politico's Reid Epstein has a story on Obama's speech that should give you an idea of the main thrust and the talking points. And the Post's Amy Gardner and Philip Rucker have some comparison between the two dueling addresses.
Update (3:10 p.m. EDT): The speech is over, lasting just less than an hour. Washington Post's The Fix blogger Chris Cillizza tweeted of the address in swing-state Ohio, "I think this is a quite smart speech by Obama. Recognition that 2 party bases are decided. TOTAL play for independents." We'll have more analysis later, and will point out the best recaps and coverage as they come out. For now, if you're interested in learning more about what Romney said, Politico's Juana Summers has a thorough recap of the candidate's "prebuttal" in Cincinnati.
Update (2:30 p.m. EDT): With Obama's speech well underway, he's spent much of the first portion of it describing Romney's economic plans, and promising to end a "stalemate" in Washington. One thing people are chattering about off the bat was CNN's decision to cut away from the speech after 10 minutes, as that's all the time they gave Romney.